Nuclear Photonics 2023

Sep 11, 2023, 4:00 AM → Sep 15, 2023, 5:00 PM America/New_York

Junior Ballroom (Durham Convention Center)

Nuclear Photonics 2023, the Fourth International Conference on Nuclear Photonics, is part of a series of biennial conferences devoted to the pursuit of nuclear science and applications with photons. 

The conference is organized by the Triangle Universities Nuclear Laboratory (TUNL), which is a research consortium of Duke University, North Carolina Central University, North Carolina State University, and The University of North Carolina at Chapel Hill.

For more information, including lodging options, visit the conference website at https://sites.duke.edu/np2023

This Indico site is intended for scheduling and storing material. Indico registration is not required for viewing, but is required to allow speakers to upload material directly.

Registering here is not sufficient to attend the conference. To register for conference attendence, please see https://sites.duke.edu/np2023/registration/ for more information.

Monday, September 11

7:30 AM → 8:30 AM Breakfest

8:30 AM → 9:00 AM Announcements: Welcoming remarks and conference information

Convener: Calvin Howell (Duke University and TUNL)

9:00 AM → 10:45 AM Nuclear Photonics Facilities

Convener: Calvin Howell (Duke University and TUNL)

9:00 AM Ultrahigh Intensity Laser Capabilities (world survey)

Speaker: Christopher Barty (University of California, Irvine)

230911 Nuclear Photonics 2023 Intense Lasers Survey SM.pdf

9:35 AM Laser Compton Sources: Present and Envisioned

A nearly monochromatic and polarized gamma-ray beam serves as a powerful tool for nuclear physics research, providing valuable insights into collective motions, strong interactions among nucleons, and the dynamics of quarks and gluons. Laser-driven Compton gamma-ray sources have been developed and operated worldwide since the late 1970s. In this presentation, we will provide an overview of the ongoing global efforts in the development and operation of laser Compton sources, with a specific focus on high-energy sources in the gamma-ray region. Using the High Intensity Gamma-ray Source (HIGS) at the Triangle Universities Nuclear Laboratory as an example, we will illustrate critical considerations to achieve a high beam flux, a small beam energy spread, and a wide operational energy range. we will highlight some of the innovative capabilities being developed at existing Compton sources. Furthermore, we will discuss potential directions for next-generation Compton gamma-ray sources driven by conventional charged particle accelerators.

This work is partially supported by DOE Grant No. DE-FG02-97ER41033.

Speaker: Ying Wu (Duke University)

NuclPhotonics_2023_YKW_final.pdf

10:10 AM The Future of Nuclear Photonics

Since our first international conference on Nuclear Photonics in Monterey in 2016, the field has developed with increasing pace. This is mostly due to developments of research infrastructure and ingenious contributions to technology, methodology, and applications made by the community, mostly by enthusiastic early-career researchers working as PhD students or postdocs. The future of Nuclear Photonics will depend on the availability of excellently trained young researchers who can benefit from the achievements made so far and are capable of carrying the field forward beyond the next five to ten years. Excellent research training on the disciplines of Nuclear Photonics in an international environment will secure this vision.

TU Darmstadt and University POLITEHNICA Bucharest have joined forces to establish an International Research Training Group (IRTG) “Nuclear Photonics” [1] addressing the needs for the vigorous development of the next generation of research leaders in the field. It will provide 100 PhD positions at Darmstadt and at Bucharest over the next nine years starting next month. Its program rests on individual highest-level research projects at the infrastructures at TU Darmstadt, GSI, and ELI-NP near Bucharest, or also here at HIγS, flanked by topical lecture courses given by its research trainers or by international guest lecturers, by a variety of international networking experiences, and by further measures for career development.

This contribution will present the IRTG framework and its program. It will also address opportunities beyond the IRTG, potential risks and challenges of the field, and it aims at initiating a discussion on present and future needs or collaborative strategies for excellent research training in Nuclear Photonics.

This activity is supported in part by the German State of Hesse under grant no. LOEWE-Research Cluster “Nukleare Photonik” and by the German Research Foundation (DFG) under grant no. IGK 2891 “Nuclear Photonics”.

[1] N. Pietralla, C.A. Ur et al., “Nuclear Photonics” Funding proposal submitted to DFG and IFA (Romania).

Speaker: Prof. Norbert Pietralla (TU Darmstadt)

NuclPhot23_talk_NPietralla_IRTG2891.pptx

NuclPhot23_talk_NPietralla_IRTG2891-webpage.pdf

10:45 AM → 11:05 AM Break

11:05 AM → 12:40 PM ELI-NP (10 PW): Capabilities and Research

Convener: Mohammad Ahmed (North Carolina Central University)

11:05 AM Status and Perspectives of ELI-NP

Extreme Light Infrastructure – Nuclear Physics (ELI–NP) [1] is the nuclear physics pillar of the pan–European Extreme Light Infrastructure project [2]. ELI–NP was implemented on the Măgurele National Physics Platform by the National Institute for R&D in Physics and Nuclear Engineering "Horia Hulubei". Two state–of–the–art sources of extreme light stay at the core of the project: a 2 x 10 PW ultra–short pulse high–power laser system and a high–intensity gamma beam system and several experimental setups were developed to take advantage of the extreme photon beams with unprecedented characteristics provided by
LI–NP.

Basic science research aims at revealing the mechanisms at the basis of particle acceleration driven by high–power lasers and to enable exotic nuclear physics experiments in plasma conditions to reproduce stellar environment evolution in laboratory. Gamma beams will enable the study of electromagnetic dipole response of nuclei and nuclear reactions of astrophysical interest. The results of the basic research will enable novel applications in life sciences, industrial and medical fields.

The high–power laser system is operational since 2020 and a thorough program of experimental setups commissioning was performed since then. The experimental setups at 100 TW and 1 PW laser powers were successfully commissioned and are available for users. The 10 PW experimental setups are under commissioning and they will become available to users in 2024. ELI–NP started operation as user facility in 2022 when the first call for users was launched in close collaboration with ELI ERIC.

The intense gamma beam system is under construction and will start operation in 2026. The experimental setups for the gamma beam were implemented providing state–of–the–art devices for nuclear physics studies. A preparatory experimental program is currently running with these detection setups on complementary science topics with the gamma beam based studies.

The ELI-NP project Phase II is co–funded by the European Union through the European Regional Development Fund and by the Romanian Govern through the Competitiveness Operational Programme.

[1] https://www.eli-np.ro .
[2] G. Mourou et al., “WHITEBOOK ELI – Extreme Light Infrastructure; Science and Technology with Ultra-Intense Lasers” (2011). doi: 10.13140/2.1.1227.0889

Speaker: Dimiter Balabanski (Extreme Light infrastructure – Nuclear Physics (ELI-NP))

balabanski_durham_0923.pptx

11:35 AM 10 PW Laser at ELI-NP

The 10 PW High Power Laser System (HPLS) at Extreme Light Infrastructure—Nuclear Physics (ELI-NP) is a dual arm laser system capable to deliver peak power laser pulses of 10 PW at 1 shot/minute repetition rate, 1 PW at 1 Hz repetition rate or 100 TW at 10 Hz repetition rate. The pulses from both arms are distributed to dedicated experimental areas: E4 for 2 x 100 TW, E5 for 2 x 1 PW and E1-E6 for the 2 x 10 PW [1]. Using the HPLS, we demonstrated for the first time in the world the propagation of 10 PW peak power pulses to an experimental area [2].

From the beginning of 2020 laser pulses at nominal power, 100 TW and 1 PW respectively, were sent towards E4 and E5 areas for commissioning experiments. From the end of 2022, the 10 PW laser beams are starting to be used in the experimental area E1 for pre-alignment, with the first 10 PW pulses on target in April 2023. In this period procedures to tune the laser parameters are developed, adapted and implemented in the HPLS.

In this presentation, we will show some of the laser parameters obtained in the experimental areas, the tuning procedures used to optimize them, and our efforts towards proper laser metrology on target. These methods rely strongly on the collaboration of the laser operation team and the experimental team. The laser parameter metrology is essential for consistent experimental results.

The Extreme Light Infrastructure—Nuclear Physics (ELI-NP) [3,4] is getting closer to becoming fully operational and it is already open for users. In the presentation, we will show statistical data on beam delivery with typical laser parameters that can be expected by the users.

This work was supported by the Extreme Light Infrastructure Nuclear Physics (ELI-NP) Phase II, a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund the Competitiveness Operational Programme 065208-5 (1/07.07.2016, COP, ID 1334), IMPULSE Project (grant 871161), and the Project PN 23210105, funded by the Ministry of Research, Innovation, and Digitalization. We gratefully acknowledge the contribution of the ELI-NP Experimental Team, Thales, and collaborators.

[1] F. Lureau et al., High-energy hybrid femtosecond laser system demonstrating 2 × 10 PW capability, High Power Laser Science and Engineering, 8, E43 (2020)
[2] C. Radier, et al., 10 pw peak power femtosecond laser pulses at ELI-NP, High Power Laser Science and Engineering, 10, (2022)
[3] S. Gales, et al., The extreme light infrastructure-nuclear physics (eli-np) facility: new horizons in physics with 10 pw ultra-intense lasers and 20 mev brilliant gamma beams.
Reports on Progress in Physics, 81(9), (2018) [4] K. A. Tanaka, et at., Current status and highlights of the ELI-NP research program, Matter and Radiation at Extremes 5(2) 024402 (2020)

Speaker: Ioan Dancus (IFIN-HH/ELI-NP)

ELI-NP - HPLS - Nuclear Photonics 2023 - v1.pdf

12:05 PM First experimental results from the 10 PW laser of ELI-NP

The commissioning of the ELI-NP experimental areas [1,2] devoted to the laser-driven experiments started in mid-2020 with the 100 TW laser arms, and continued with the 1 PW arms until last year. Eventually, this year the first shot in the world at 10 PW [3,4] was fired on April 13. The experimental campaign started at the end of last year when the 10 PW laser beam was delivered to the interaction chamber dedicated to experiments with the short focal parabolic mirror. Initially, fundamental laser properties such as focusability, pulse duration, and pointing were investigated and shown to be remarkably good. The laser was focused down to 2.8 μm at FWHM, the pointing stability was better than 2 μrad, and the pulse duration was around 24 fs. The encircled laser energy was measured to be about 50%, therefore allowing for an effective laser peak intensity on target of about 6 x 10$^{22}$ Wcm$^{-2}$. The high-power shots were performed through a single plasma mirror both to improve the laser temporal contrast and reduce the probability of back-reflected laser light. To investigate the performance of the laser we have studied the proton acceleration via TNSA mechanism. For this purpose, several diagnostics were implemented to gather diverse information on the interaction of the laser with a solid target. Proton energies exceeding 100 MeV have been attained, even if the laser temporal contrast is affected by a few pre-pulses, that have been identified and partially fixed during the commissioning.

In this talk, the preliminary results obtained with the 10 PW laser system will be presented.

This work was supported by the Extreme Light Infrastructure Nuclear Physics (ELI-NP) Phase II, a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund the Competitiveness Operational Programme 065208-5 (1/07.07.2016, COP, ID 1334), IMPULSE Project (grant 871161), and the Project PN 23210105, funded by the Ministry of Research, Innovation, and Digitalization. We gratefully acknowledge the contribution of the ELI-NP Laser Team, Thales, and collaborators (QUB-UK, CLF-RAL-UK, KPSI-QST-Japan, Osaka University-Japan, HZDR-Germany, UCSD-USA, University of Strathclyde-UK, LLE-USA, ELI-BL-CZ).

[1] D. Doria et al., “Overview of ELI-NP status and laser commissioning experiments with 1 PW and 10 PW class-lasers”, JINST, 15, C09053 (2020).
[2] K. A. Tanaka, et at., “Current status and highlights of the ELI-NP research program”, Matter and Radiation at Extremes 5(2) 024402 (2020)
[3] F. Lureaux et al., “10 petawatt lasers for extreme light applications”, Proc. SPIE 11259, Solid State Lasers XXIX: Technology and Devices, 112591J (2020)
[4] F. Lureau et al., “High-energy hybrid femtosecond laser system demonstrating 2 × 10 PW capability”, High Power Laser Science and Engineering, 8, E43 (2020)

Speaker: Viorel Nastasa (Extreme Light infrastructure – Nuclear Physics (ELI-NP))

VN Nuclear Photonics_2023_fin.pdf

12:40 PM → 2:00 PM Lunch

2:00 PM → 4:10 PM Nuclear Structure Studies with photons

Convener: Anton Tonchev (Lawrence Livermore National Laboratory)

2:00 PM Broadband and high-brilliance gamma-ray beams for studies of fundamental nuclear low-multipole modes

The advantages of combining broadband bremsstrahlung beams and highly-brilliant gamma-ray beams from Compton back-scattering will be discussed on the basis of recent experimental programs. Due to the low angular momentum transfer through real photons, the sensitivity of such studies [1] is high for low multipoles, i.e., in particular for the electric and magnetic dipole response, but also for electric quadrupole excitations. Therefore, much experimental effort in recent years has gone into fostering a better understanding of the electric dipole response of atomic nuclei, which is dominated by the electric giant dipole resonance. Although this mode is known since the first days of photo-excitation experiments, some of its properties are yet to be determined, as well as the detailed structure on its low-energy tail, which eventually includes the so-called pygmy dipole resonance. The electric dipole response remains under active discussion, due to structural aspects and to better understand photon strength functions, which are one important ingredient in connection to nucleosynthesis [2]. Also important for photon strength functions is the magnetic dipole response, which includes fundamental modes such as the nuclear scissors mode and the isovector-M1 spin-flip resonance. The latter is of particular interest for astrophysical scenarios, due to the similarity between the spin-flip M1 and the Gamov-Teller operators. Data on the M1 response may, thus, constrain electron-capture rates for supernova scenarios [3], but is also important in view of coherent neutrino scattering, which excites in particular spin-flip M1 states [3]. Furthermore, real photons allow insight on E2 properties of nuclei, especially the first (collective) quadrupole excitations of even-even isotopes, hence, may give model-independent insight into the evolution of E2 strengths in nuclei [5,6].

This research is supported in part by the German DFG under contract no. 279384907-SFB 1245 and BMBF under grant no. 05P21RDEN9, as well as the State of Hesse within the LOEWE program “Nuclear Photonics”.

[1] A. Zilges, D.L. Balabanski, J. Isaak, and N. Pietralla, Prog. Part. Nucl. Phys. 122, 103903 (2022).
[2] S. Goriely, Phys. Lett. B 436, 10 (1998).
[3] K. Langanke, G. Martínez-Pinedo, and R.G.T. Zegers, Rep. Prog. Phys. 84, 066301 (2021).
[4] E. Ydrefors, K.G. Balasi, t.S. Kosmas, and J. Suhonen, Nucl. Phys. A 896, 1 (2012).
[5] T. Beck et al., Phys. Rev. Lett. 118, 212502 (2017).
[6] K.E. Ide et al., Phys. Rev. C 103, 054302 (2021).

Speaker: Volker Werner (TU Darmstadt)

2:35 PM Investigation of nuclear structure with resonant photon scattering at the HIγS facility

Photon beams are a highly selective probe of the charge and current distributions of nuclei. The specific spin selectivity and strength sensitivity of this probe enables an almost model-independent spectroscopic study of dipole excitations at energies up to the particle emission threshold and investigations of the collective response of the internal degrees of freedom of the nucleus. In this talk, recent developments and experimental results of nuclear structure studies obtained from photonuclear reactions with nearly-monoenergetic, polarized photon beams from the HIγS facility at TUNL will be presented and compared with those obtained with hadron-induced reactions.

Speaker: Akaa Ayangeakaa (University of North Carolina at Chapel Hill and TUNL)

3:10 PM Test of the B(E2) evolution in the Sn isotopic chain with photons

With its long chain of experimentally accessible isotopes, the Sn isotopes with their closed Z=50 proton shell are a fertile testing ground for nuclear structure models. Yet, there is debate on basic properties, even of stable Sn isotopes, namely, the B(E2) excitation strengths of their first-excited 2$^+$ states. Experiments toward the neutron-deficient isotopes revealed unexpectedly large B(E2) values, which had been related to enhanced quadrupole correlation due to the particular neutron orbitals filled at the beginning of the shell, whereas the structures of heavier isotopes are seniority dominated. This structural transition has been described as a phase transition between both regimes within a Monte Carlo shell model approach [1], yielding a local minimum in B(E2) values at $^{116}$Sn. The particulars of the structural transition, however, differ in other model approaches. Data, mostly obtained through Coulomb-excitation and Doppler-shift techniques (see, e.g., [2,3]) show conflicting trends and magnitudes of B(E2) strengths.

We used an alternative method, nuclear resonance fluorescence [4], exploiting the purely electromagnetic interactions between photons and nuclei, to probe the B(E2) strength across the predicted minimum at N=66, avoiding uncertainties of nuclear interactions or stopping powers of ions in materials. The isotopes $^{112,116,120}$Sn have been measured at the bremsstrahlung facility, DHIPS, at the S-DALINAC at TU Darmstadt in three experiments. Therein, we measured the E2 excitation strengths of the first 2+ states of $^{116,120}$Sn relative to that of $^{112}$Sn, hence, avoiding any potential systematic error from absolute scales. In addition, we measured the E2 excitation strength of the 2$_1^+$ state of $^{112}$Sn relative to well-known excitation cross sections in other isotopes, in order to determine the absolute scale of E2 strengths in the Sn isotopes. The new results indicate a rather smooth change-over between the quadrupole-collective and seniority schemes around N=66, and are in agreement with several sets of Coulomb-excitation data.

This research is supported in part by Deutsche Forschungsgemeinschaft – Project-ID 279384907 – SFB 1245, and by the State of Hesse within the LOEWE research project “Nuclear Photonics”.

[1] T. Togashi, Y. Tsunoda, T. Otsuka, N. Shimizu, and M. Honma, Phys. Rev. Lett. 121, 062501 (2018).
[2] A. Jungclaus et al., Phys. Lett. B 695, 110 (2011).
[3] M. Allmond et al., Phys. Rev. C 92, 041303 (2015).
[4] A. Zilges, D. Balabanski, J. Isaak, and N. Pietralla, Prog. Part. Nucl. Phys. 122, 103903 (2022).

Speaker: Maike Beuschlein

Nuclear-Structure-Studies-with-photons_MBeuschlein.pdf

3:30 PM Gamma strength function of Fe-56 from photon scattering

We investigate the dipole strength distributions in $^{56}$Fe using the nuclear resonance fluorescence (NRF) technique with 100% linearly polarized photons for incident beam energies below the neutron separation energy (~11 MeV) at the High Intensity Gamma-ray Source (HIgS) facility at the Triangle Universities Nuclear Laboratory. Preliminary NRF results of observed dipole states and their transition strengths will be compared with theoretical calculations based on the energy-density functional theory and quasi-particle phonon model [1]. We will determine the photon scattering cross sections from the measured elastic/ground state and inelastic transitions and then deduce the gamma-strength function (gSF) of $^{56}$Fe [2]. The measured NRF gSF will be compared with literature data obtained via the Oslo method [3,4] in which the low-energy enhancement, or upbend, has been observed. With the recent upgrade of the high-efficiency clover detector array and the increased g-ray flux at HIgS, we aim to study these low-energy primary g-ray transitions induced by incident photon beams using coincidence measurements to provide a multi-faceted understanding of the upbend phenomenon.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

[1] N. Tsoneva and H. Lenske, Physics of Atomic Nuclei 79, 885 (2016).
[2] A.P. Tonchev et al., Phys. Rev. Lett. 104, 072501 (2010).
[3] A.V. Voinov et al., Phys. Rev. C 74, 014314 (2006).
[4] A.C. Larsen et al., Phys. Rev. Lett. 111, 242504 (2013).

Speaker: Anthony Ramirez (Lawrence Livermore National Laboratory)

3:50 PM Evaluation of Photonuclear Cross-Section for Light Nuclei

A diverse set of probes has confirmed two-nucleon (2N) short-ranged correlated structures inside nuclei, mainly in n-p form [1]. Additionally, some light nuclei of astrophysical importance, like $^7$Li and $^7$Be, exhibit clear signatures of loosely bound 3N structures with core-α [2]. Moreover, the energetic photons in GDR and quasi-deuteron regions are expected to interact with few-nucleon correlated structures and clusters present in light nuclei. Hence, the photonuclear reaction cross-section for light nuclei like $^6$Li, $^7$Li, $^7$Be, $^{12}$C, $^{15}$N, $^{16}$O etc., can be evaluated by summing the cross-sections of their constituent 2N, 3N correlated structures and clusters. After a detailed analysis of the photonuclear processes for deuteron, tritium, $^3$He, and $^4$He and assuming that the photonuclear cross-section of quasi-deuterons/quasi-tritium/quasi-$^{3}$He and $\alpha$-cluster can be evaluated by scaling the appropriate expression for their free counterparts, we have obtained the photonuclear reaction cross-sections for light nuclei [3-4]. A significant fraction of the GDR cross-section may be accounted for by the contribution of the quasi-$\alpha$ degree of freedom [3], which decreases for higher E$\gamma$. Contrary to general perception, the quasi-deuteron photonuclear contribution starts in the GDR region itself and dominates for E$\gamma$ > 50 MeV. The present work also illuminates the microscopic origin of the Levinger formula, the damping factor for the quasi-deuteron cross-section at lower Eγ values, and an explanation for the double peak excitation function for the $^6$Li photonuclear reaction [2], etc. Some of the testable predictions for the current approach are also outlined.

[1] R. Dalal and MacGregor I. J. D, “Nucleon-nucleon correlations inside atomic nuclei: synergies, observations and theoretical models,” https://doi.org/10.48550/arXiv.2210.06114
[2] M. R. Sené et al., “The 7Li(γ, N) and 7Li(e, N) reactions at intermediate photon energies,” Nucl. Phy. A, 442, 215 (1985).
[3] R. Dalal and R. Beniwal, “Photo-disintegration of N=Z light nuclei using SRC-based approach,” PoS (PANIC2021), 380, 323 (2021).
[4] R. Beniwal and R. Dalal, SRC based model for the photonuclear reactions on N=Z light nuclei, Accepted in Phy. At. Nucl. (2023).

Speaker: Ranjeet Dalal (Guru Jambheshwar University of Science and Technology)

Nuclear-photonics-2023-Ranjeet.pptx

Paper-on-photonuclear-reactions-on-n=z-light-nuclei.pdf

4:10 PM → 4:30 PM Break

4:30 PM → 6:00 PM Laser-Compton Sources: gamma-ray beam Innovations, applications and QCD

Convener: Ying Wu (Duke University)

4:30 PM Experimental study of orbital angular momentum beams using a free-electron laser oscillator

Orbital angular momentum (OAM) photon beams provide a unique tool for nondestructive photon-matter interactions in a broad photon energy range. Here, we report the first experimental demonstration of coherently mixed OAM beams from an oscillator free-electron laser (FEL). With wavelength tunability, free-electron lasers (FELs) are well-suited for generating OAM beams in a wide photon energy range. Lasing around 458 nm, we have generated OAM FEL beams up to the fourth order, as a coherent superposition of two pure OAM modes with opposite helicities. These coherently mixed OAM beams are generated with high quality in terms of beam quality factors and mode components, high degree of circular polarization, and high power. We have also developed a pulsed mode operation of the OAM beam with a highly reproducible temporal structure for a range of modulation frequencies from 1 to 30 Hz. This development can be extended to short wavelengths, for example to x-rays using a future x-ray FEL oscillator. The operation of such an OAM FEL also paves the way for the generation of OAM gamma-ray beams via Compton scattering. We will also discuss the challenges of producing high-flux OAM gamma-ray beams with the Compton scattering scheme using an electron beam and an OAM laser beam.

This research is supported in part by the U.S. Department of Energy under Grant No. DE-FG02-97ER41033.

Speaker: Peifan Liu

Peifan_Liu_Nuclear-Photonics_092023.pdf

5:00 PM 2D and 3D Imaging by Nuclear Resonance Absorption/Fluorescence Using Extremely Brilliant Compton Sources

Nuclear resonance absorption/fluorescence (NRA/F) is the process by which a nucleus absorbs/emits electromagnetic radiation. Because the energy of this process is specific to the isotope, interrogating nuclear energy levels electromagnetically has been proposed for solutions in nuclear materials detection and pharmaceutical purity measurements [1]. Jentschel et al. recently demonstrated how a 1D transmission projection could be performed by using monoenergetic x-rays tuned to the 478 keV $^7$Li first excited state [2]. This paper outlines how NRA/F can be used to do isotope-specific imaging in higher dimensions, with particular emphasis on possible medical applications but can be extended to any imaging application.

The absorption cross section for these nuclear energy levels is exceedingly narrow, with Doppler-broadened ΔE/E widths as small as 10$^{-6}$ . Therefore, a source that has narrow energy bandwidth is a requirement to obtain appreciable signal from these transitions. Extremely brilliant Compton sources (EBCSs) are well-suited for probing these transitions as they are high in brilliance and are designed to have 10$^{-3}$ on-axis energy bandwidth with capability to reach 10$^{-5}$ after bandwidth filtering.

A 4.2 cm thick water phantom with 2- and 3-mm radii spheres of gadolinium was used. Geant4 was used to simulate the x-ray interactions with the G4NRF package for NRA/F physics. A simulated Compton source that is tuned to on-axis energy being the energy of the NRA line and a second image is obtained tuning the energy just below the NRA line. Experimental methods for obtaining these images will be discussed, as well as extensions to 3D images and use of different isotopes that are of medical relevance, like gadolinium.

[1] J. Pruet, et al., “Detecting clandestine material with nuclear resonance fluorescence,” Journal of Applied Physics, 99, 123102 (2006).
[2] M. Jentschel, et al., “Isotope-selective radiography and material assay using high-brilliance, quasi-monochromatic, high-energy photons,” Applied Optics, 61(6), C125 (2022).

Speaker: Trevor Reutershan (University of California - Irvine)

Reutershan_nuclear_photonics_2023.pdf

Reutershan_nuclear_photonics_2023.pptx

5:20 PM Two and Three-body Photodisintegration of the Triton at Energies Below 30 MeV

Photonuclear reactions are sensitive to nuclear currents that are not accessible in pure hadronic processes and therefore, provide important insights to deepen our understanding of the few nucleon systems. However, the lack of kinematically-complete three-nucleon data remains a major hurdle in benchmarking the theoretical formalisms which are employed to model these few nucleon systems.

To that end, preparations are underway at the High-Intensity Gamma-Ray Source (HIγS) at the Triangle Universities Nuclear Laboratory (TUNL) to perform a kinematically-complete measurement of the tritium photodisintegration cross section. The proposed experiment will measure both two-body and three-body photodisintegration cross sections of tritium at incident photon energies below 30 MeV using the quasi-monoenergetic photon beam at HIγS.

The experiment will use a pressurized tritium gas target (200 psi) with thin aluminum windows (0.25 mm) for beam entrance and exit. Outgoing neutrons will be detected using an array of liquid organic scintillators. The gas target will be placed inside a secondary containment system equipped with tritium monitors during the experiment for radiation safety.

This experiment will be carried out by a collaboration of groups from TUNL and the Laboratory for Laser Energetics (LLE) at the University of Rochester. The target cells will be fabricated and pressure-tested at TUNL before being sent to LLE for tritium gas diffusion measurements using the tritium gas handling infrastructure at the LLE.

In this talk, we present the preparation and radiation safety infrastructure development for this experiment.

This research is supported by the U.S. Department of Energy under Contracts DE-SC0022573 and DE-FG02-97ER41033.

Speaker: Danula Godagama (Duke / TUNL)

NP2023_3.pdf

5:40 PM Results of the GRIT photoinjector commissioning at RadiaBeam

The generation of high spectral brilliance radiation with electron beam sources relies heavily on the qualities of the electron beam. Achieving a remarkably high electron beam brightness necessitates a combination of high peak current and low emittance. These characteristics are made possible through the utilization of intense field acceleration in a radio-frequency (RF) photoinjector source. However, despite the current utilization of high fields, certain limitations exist on the achievable peak current for high brightness operation, typically in the range of tens of Amperes.

To overcome this limitation, a hybrid structure combining standing wave and traveling wave components proves to be effective [1]. The standing wave section facilitates high-field acceleration from the photocathode, while the traveling wave portion induces strong velocity bunching. This remarkably compact injector system offers the additional advantage of simplifying the distribution of RF power by eliminating the need for the RF circulator. We explore the application of this device in a compact 4.5 MeV electron source for further acceleration up to 100 MeV, enabling both inverse Compton scattering and free-electron laser radiation sources with distinctive and appealing properties.

Within the scope of this research, we undertake the commissioning of the high-field hybrid photoinjector electron source operating in a C-band frequency. Overview of the Hybrid photoinjector and its design features are revealed in this work. Main electron beam parameters such as energy gain and spread, bunch length, charge yield, and transverse emittance were measured in order to justify the photoinjector’s optimal operational parameters. Reported in this work commissioning results will substantiate the foundation for further harnessing hard X-ray from inverse Compton scattering of the IR laser on the electron beam.

[1] L. Faillace, et. al, “High field hybrid photoinjector electron source for advanced light source applications”, Phys. Rev. Accel. Beams, 25, 063401 (2022)

Speaker: Maksim Kravchenko (RadiaBeam Technologies)

6:00 PM → 6:10 PM Announcements

Convener: Calvin Howell (Duke University and TUNL)

6:30 PM → 8:00 PM Dinner

8:00 PM → 10:00 PM Poster: Setup

Tuesday, September 12

7:30 AM → 8:30 AM Breakfest

8:30 AM → 8:45 AM Announcements

Convener: Calvin Howell (Duke University and TUNL)

8:45 AM → 10:35 AM Strong-Field QED and High Intensity Laser-Plasma Interaction

Convener: Christopher Barty (University of California - Irvine)

8:45 AM Laser-plasma electron acceleration and gamma-ray generation with PW laser pulses

Laser wakefield acceleration (LWFA) [1] and x-ray/gamma-ray generation based on LWFA [2] are emerging technologies that exhibit promising advancements in the production of compact, high-energy electron and photon sources. The advent of PW and multi-PW lasers [3–5] has facilitated the investigation of new regimes of LWFA and radiation generation. We recently conducted a LWFA experiment with 2.5-PW laser pulses and obtained a high-quality 4.5 GeV electron beam from a helium gas cell containing 1% neon dopant. Compared to a pure helium medium, the neon dopant significantly increased the energy spread, charge, and divergence of the electron beams. Numerical studies utilizing particle-in-cell simulations revealed that sequential ionization of neon dopants played a crucial role in laser propagation, whereas ionization injection induced by inner-shell ionization [6] of neon occurred only at the position of strong self-focusing. These results demonstrate the importance of neon dopants in the production of high-quality multi-GeV electron beams utilizing multi-PW laser pulses. In addition, we achieved high-brightness, high-flux betatron radiations in the gamma-ray range by separating the radiation generation process from the acceleration process, a method known as the hybrid betatron scheme [7]. In this presentation, we will discuss recent developments in LWFA and hybrid betatron gamma-ray generation utilizing laser pulses with multiple PW.

[1] T. Tajima and J. M. Dawson, Laser Electron Accelerator, Phys. Rev. Lett. 43, 267 (1979).
[2] F. Albert and A. G. R. Thomas, Applications of Laser Wakefield Accelerator-Based Light Sources, Plasma Phys. Control. Fusion 58, 103001 (2016).
[3] J. H. Sung, S. K. Lee, T. J. Yu, T. M. Jeong, and J. Lee, 0.1 Hz 1.0 PW Ti:Sapphire Laser., Opt. Lett. 35, 3021 (2010).
[4] J. H. Sung, S. K. Lee, H. W. Lee, J. Y. Yoo, and T. M. Jeong, 0 . 1 Hz 4 . 0 PW Ti : Sapphire Laser at CoReLS, 42, 3 (2017).
[5] J. W. Yoon, Y. G. Kim, I. W. Choi, J. H. Sung, H. W. Lee, S. K. Lee, and C. H. Nam, Realization of Laser Intensity over 10 23 W/Cm 2 , Optica 8, 630 (2021).
[6] A. Pak, K. A. Marsh, S. F. Martins, W. Lu, W. B. Mori, and C. Joshi, Injection and Trapping of Tunnel-Ionized Electrons into Laser-Produced Wakes, Phys. Rev. Lett. 104, 025003 (2010).
[7] J. Ferri et al., High-Brilliance Betatron γ -Ray Source Powered by Laser-Accelerated Electrons, Phys. Rev. Lett. 120, 254802 (2018).

Speaker: Hyung Taek Kim (Gwangju Institute of Science and Technology)

9:15 AM Accessing light-by-light scattering with XFEL and high-intensity laser pulses

Quantum field theory predicts the vacuum to exhibit a non-linear response to strong electro-magnetic fields [1]. This fundamental tenet has remained experimentally challenging and is yet to be tested in the laboratory [2]. Macroscopic electromagnetic fields available in the laboratory fulfill $\left\{ \left|\overrightarrow{E}\right|,c\left|\overrightarrow{B}\right|\right\} \ll E_{S}$, with $E_{S}=m^{2}c^{3}/\left(e\hbar\right)$ set by QED parameters: the electron mass m and elementary charge e. If these fields vary on scales much larger than the Compton wavelength of the electron $\lambda_{C}=\hbar/\left(mc\right)\simeq1.3\times10^{18}m$, their leading interactions are governed by $\left(c=\hbar=1\right)$

$\mathcal{L}_{int}\simeq\frac{m^{4}}{1440\pi^{2}}\left[a\left(\frac{\overrightarrow{B}^{2}-\overrightarrow{E}^{2}}{E_{S}^{2}}\right)^{2}+b\left(\frac{2\overrightarrow{B}\cdot\overrightarrow{E}}{E_{S}^{2}}\right)^{2}\right] $.

The constants a and b control the strength of the four-field couplings. QED predicts these to have a series expansion in $\alpha=e^{2}/\left(4\pi\right)\simeq1/137$ and read [1,3]

$a=4\left(1+\frac{40}{9}\frac{\alpha}{\pi}+\ldots\right)$, $b=7\left(1+\frac{1315}{252}\frac{\alpha}{\pi}+\ldots\right)$.

We present proof of concept and detailed theoretical analysis of an experimental setup for precision measurements of the quantum vacuum signal generated by the collision of a brilliant x-ray probe with a high-intensity pump laser [4]. Our proof-of-concept measurements show that the background can be efficiently suppressed by many orders of magnitude. This should facilitate a detection of both polarization components (⊥, ∥) of non-linear vacuum response and thereby provide direct access to the low-energy constants a and b governing light-by-light scattering.

[1] W. Heisenberg and H. Euler, Z. Phys. 98, 714 (1936).
[2] A. Fedotov, et al.Phys. Rept. 1010, 1-138 (2023).
[3] V. Ritus, J. Exp. Theor. Phys. 42, 774 (1975).
[4] F. Karbstein, D. Ullmann, E. A. Mosman and M. Zepf, Phys. Rev. Lett. 129, 061802 (2022).

Speaker: Felix Karbstein (Helmholtz Institute Jena)

Tu1.15-Karbstein.pdf

9:45 AM Photon Vortex Production from Synchrotron Radiation in Relativistic Quantum Approach

Photon vortices caring orbital angular momentum (OAM) [1] with a wave function of Laguerre Gaussian (LG) wave or Bessel wave are one of the most interesting topics in various fields of physics. The interaction between a photon vortex and a material such nucleus may be different from that with standard photons because the photon vortex has non-zero orbital angular momentum parallel to the direction of the photon propagation. It is expected that photon vortices are created in astronomical systems such as black holes [2]. Gamma-ray bursts (GRBs) are one of the most energetic explosive phenomena in the universe, where highly linear (circular) polarization in the energy region of several hundred keV was observed. It may be generated by synchrotron radiations from relativistic electrons under strong magnetic fields.

In quantum theory, electron orbitals in a magnetic field are under Landau states. In the present work we have calculated the photon vortex production from a spiral moving electron under a uniform magnetic field with the strength of 10$^7$-10$^8$ T taking into account Landau quantization. We have theoretically presented that photon vortices are predominantly generated in astrophysical environments with strong magnetic fields such as magnetars or magnetized accretion disks around black holes [3]. This suggests that nucleosynthesis with photons should be changed from that with standard photons. A photon vortex is generated through a transition of an electron between two Landau levels and has a Bessel wave-function. We also calculate the decay widths from an electron in Landau levels and the energy spectra. The present result suggests a possibility that magnetic fields in neutron stars such as magnetar play an important role in the interpretation of many observed phenomena. Magnetars show properties different than normal neutron stars. Particularly large luminosity of photon and neutrino emission attract attention from many researchers.

By the way, this subject can be confirmed by experiments in the laborattory. However, the strength of the magnetic field that can be realized in the laboratory is up to 10 T, and when the Larmor radius is 10 mm, the number of Landau levels of an incident electron is huge, approximately 10$^5$. Recently, we have succeeded in developing a theoretical method to calculate photon vortex production from such a huge Landau level number. This will be presented in the paper.

[1] L. Allen, et al. Phys. Rev. A 45, 8185 (1992).
[2] F. Tamburini, et al. Nature Phys. 7, 195 (2011).
[3] T. Maruyama, et al. Phys. Lett. B826. 136779 (2022).

Speaker: Tomoyuki Maruyama (College of Bioresource Sciences, Nihon university)

NcPh_Maruyama.pdf

10:15 AM Undepleted Direct Laser Acceleration

For the past two decades, intense lasers have supported new schemes for generating high-energy particle beams in university-scale laboratories. With the direct laser acceleration (DLA) method, the leading part of the laser pulse ionizes the target material and forms a positively charged ion plasma channel into which electrons are injected and accelerated. DLA has been realized over a wide range of laser parameters, using low-atomic-number target materials. A striking result is the extremely high conversion efficiency from laser energy to MeV electrons, with reported values as high as 23% [6], which makes this mechanism ideal for generating large numbers of photo-nuclear reactions [4]. DLA is well understood and reproduced in numeric simulations. Specifically, the electron beam energy has been confirmed to scale with the normalized laser intensity up to values of 𝑎$_0$ ∼1.5 [2]. However, the electron energies obtained with the highest laser intensities available nowadays [4,6], fail to meet the prediction of these scaling laws [5]. Here we reveal that at these higher laser intensities, the leading edge of the laser pulse depletes the target material of its ionization electrons prematurely. We demonstrate that for efficient DLA to prevail, a target material of sufficiently high atomic number is required to maintain the injection of ionization electrons at the peak intensity of the pulse when the DLA channel is already formed. Applying this new understanding to experiments on multi-petawatt laser facilities now coming online is expected to increase the electron energy overlap with the neutron production cross-sections of any material. These increased neutron yields are required to enable a wide range of research and applications, such as investigation of nucleosynthesis in the laboratory [1], performing non-destructive material analysis [7], and industrial applications [3].

[1] S. N. Chen, F. Negoita, K. Spohr, E. D’Humières, I. Pomerantz, and J. Fuchs. Extreme brightness laser-based neutron pulses as a pathway for investigating nucleosynthesis in the laboratory. Matter and Radiation at Extremes, 4(5):054402, sep 2019.
[2] C. Gahn, G. D. Tsakiris, G. Pretzler, K. J. Witte, P. Thirolf, D. Habs, C. Delfin, and C. G. Wahlström. Generation of MeV electrons and positrons with femtosecond pulses from a table-top laser system. Physics of Plasmas, 9(3):987, 2002.
[3] Christian Grünzweig, David Mannes, Anders Kaestner, Florian Schmid, Peter Vontobel, Jan Hovind, Stefan Hartmann, Steven Peetermans, and Eberhard Lehmann. Progress in Industrial Applications using Modern Neutron Imaging Techniques. Physics Procedia, 43:231–242,
jan 2013.
[4] I. Pomerantz, E. McCary, A. R. Meadows, A. Arefiev, A. C. Bernstein, C. Chester, J. Cortez, M. E. Donovan, G. Dyer, E. W. Gaul, D. Hamilton, D. Kuk, A. C. Lestrade, C. Wang, T. Ditmire, and B. M. Hegelich. Ultrashort pulsed neutron source. Physical Review Letters, 113(18):1–6, 2014.
[5] A. Pukhov, Z. M. Sheng, and J. Meyer-ter Vehn. Particle acceleration in relativistic laser channels. Physics of Plasmas, 6(7):2847–2854, 1999.
[6] Olga Rosmej, Mikhail Gyrdymov, Marc M Günther, Nikolay E Andreev, Parysatis M Tavana, Paul Neumayer, Sero Jakob Zähter, Nadiya Zahn, Viacheslav S Popov, Nataliya Borisenko, Alexey Kantsyrev, Aleksey Skobliakov, Vsevolod Panyushkin, Anton Bogdanov, Fabrizio Consoli, Xiaofei F Shen, and Alexander Pukhov. High-current laser-driven beams of relativistic electrons for high energy density research. Plasma Physics and Controlled Fusion, aug 2020.
[7] Marc Zimmer, Stefan Scheuren, Annika Kleinschmidt, Nikodem Mitura, Alexandra Tebartz, Gabriel Schaumann, Torsten Abel, Tina Ebert, Markus Hesse, Sêro Zäahter, Sven C. Vogel, Oliver Merle, Rolf Jürgen Ahlers, Serge Duarte Pinto, Maximilian Peschke, Thorsten Kröll, Vincent Bagnoud, Christian Rödel, and Markus Roth. Demonstration of non-destructive and isotope-sensitive material analysis using a short-pulsed laser-driven epi-thermal neutron source. Nature Communications 2022 13:1, 13(1):1–11, mar 2022.

Speaker: Ishay Pomerantz (Tel Aviv University)

Undepleted-DLA-NP2023.pdf

10:35 AM → 11:05 AM Break

11:05 AM → 12:25 PM Inertial Confinement Fusion

Convener: Calvin Howell (Duke University and TUNL)

11:05 AM Progress in Laser Direct-Drive Inertial Confinement Fusion

Recent progress in cryogenic DT-layered implosion experiments on the OMEGA laser have considerably improved the prospects for achieving thermonuclear ignition and energy gains with megajoule-class lasers via direct drive. By hydrodynamically scaling the core conditions of highest performing OMEGA implosions [1], fusion yields above a megajoule are expected for 2 MJ of symmetric laser illumination [2]. Those implosions have benefited from a significant increase in implosion performance obtained through a statistical approach used in predicting implosion experiments and designing targets and laser pulse shapes [3,4] to achieve the highest implosion velocity while maintaining hydrodynamic stability. It is now possible to separate individual contributions to the yield degradation providing a more complete physics picture for each implosion. To test individual degradation mechanisms, dedicated implosion experiments have been carried out by implementing single parameter scans. Scans of the SSD (Smoothing by Spectral Dispersion) bandwidth [5,6] to study laser imprinting; scans of the stalk mount size are used to study effects of engineering features; scans of the vapor pressure are used to study the effects of higher implosion convergence. An overview of the implosion optimization effort and of the dedicated physics experiments at the OMEGA laser will be provided.

[1] C.A. Williams et al, submitted to Nature Physics (2023); C.A. Williams at this conference.
[2] V. Gopalaswamy et al, submitted to Nature Physics (2023);
[3] V. Gopalaswamy et al, Nature 565, 581-586 (2019)
[4] A. Lees et al, Phys. Rev. Lett. 125, 105001 (2021); A. Lees at this conference
[5] D. Patel et al, Submitted to Phys. Rev. Lett. (2023)
[6] J.P. Knauer et al, Bulletin American Physical Society, Invited Presentation NI02.00002, (2022)

This material is based upon work supported by the Department of Energy Office of Fusion Energy Sciences under award DE-SC0022132, the National Nuclear Security Administration under Award Numbers DE-NA0003856, DE-NA0003868, the University of Rochester, and the New York State Energy Research and Development Authority. In collaboration with the LLE Experimental and Theory Divisions, the OMEGA facility team, the LLE Target Fabrication group, the LLE Cryogenic and Tritium group, the General Atomics target fabrication group and the HEDP Division at the MIT-PFSC.

Speaker: Riccardo Betti (Laboratory for Laser Energetics (LLE), University of Rochester)

Betti-Nuclear-Photonics-v6.pdf

11:40 AM National Ignition Facility: Nuclear Fusion Breakthrough

Groundbreaking advancements have been made in Inertial Confinement Fusion (ICF) research at the National Ignition Facility (NIF), resulting in experiments that have surpassed Lawson's criterion and have demonstrated a gain (G) greater than unity [1]. Improving the gain in ICF requires achieving higher areal densities, exceeding 1.5 g/cm2, assembled via spherical compression to confine the fuel while the thermonuclear burn wave consumes more than 10% of the deuterium-tritium fuel. In this presentation, we will provide an overview of the ICF implosions that have achieved ignition on the NIF. Additionally, we will delve into the ongoing efforts to increase compression in ICF experiments to attain even higher gains (G >> 1).

This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

[1] H. Abu-Shawareb et al., PRL 129, 075001 (2022).

Speaker: Benjamin Bachmann (Lawrence Livermore National Laboratory)

12:25 PM → 2:00 PM Lunch

2:00 PM → 4:10 PM Photon-induced Fission

Convener: Volker Werner (TU Darmstadt)

2:00 PM Simultaneous measurement of fragment mass, energy, and angular distributions from (γ,f) reactions

Although fission was discovered over 80 years ago and has seen widespread usage, a complete microscopic description of the fission process is yet to be achieved. One important contribution towards that objective is high-precision experimental data. In particular, nuclear fission induced by quasi-monochromatic polarized photons provides unique information due to their selectivity on low-multipolarity excitations, thereby learning about the potential energy landscape around the multi-humped fission barrier as well as determining transition states and channels through which the fission process proceeds.

Measuring mass, total kinetic energy, and polar as well as azimuthal angular distributions of the fission fragments simultaneously in the same detector allows correlations to be examined, e.g. between fragment mass and the identification of transition states. After a brief overview over previous experiments on photofission, this talk will showcase recent ($\gamma$,f) experiments performed at the High-Intensity $\gamma$-ray Source (HI$\gamma$S) at Triangle Universities Nuclear Laboratory (TUNL) using a position-sensitive twin Frisch-grid ionization chamber [1]. We will present results of a pioneering $^{238}$U($\gamma$,f) experiment at an excitation energy of 11.2 MeV [2] as well as early data from a follow-up $^{234}$U($\gamma$,f) experiment investigating multiple excitation energies, including values near the fission barrier.

Supported by HMWK (LOEWE Cluster Nuclear Photonics)

[1] A. Göök et al., “A position-sensitive twin ionization chamber for fission fragment and prompt neutron correlation experiments”, Nucl. Instrum. Methods A, 830, 366 (2016); M. Peck et al., “Performance of a twin position-sensitive Frisch-grid ionization chamber for photofission experiments”, EPJ Web of Conferences, 239, 05011 (2020).
[2] M. Peck, “Correlation experiments in photon-induced nuclear fission”, Dissertation, Technische Universität Darmstadt (2020).

Speaker: Vincent Wende (Technische Universität Darmstadt)

NP_2023_Wende.pdf

2:35 PM Double Differential Measurements of Prompt Neutron Emission from Photoninduced Reactions on Actinides

Photonuclear reactions offer a unique probe of the nucleus due to lack of hadronic processes in the entrance channel. This is of particular interest for studying the prompt neutrons emitted during fission, which is more typically initiated with neutrons. Two types of measurements of prompt neutrons emitted from photon-induced fission will be presented.

At photon beam energies between about 10 and 15 MeV where the fission cross section is sufficiently high, active targets were used to tag fission events associated with detection of prompt neutrons. The $\gamma$-ray beam is nearly monoenergetic and pulsed with a width of 0.3 ns FWHM and a period of 179.2 ns. The neutrons were detected in an array of liquid organic scintillators, and the kinetic energy of each detected neutron was determined using time-of-flight methods.

Measurements below 10 MeV are motivated by efforts to develop bremsstrahlung-based active interrogation systems for detecting special nuclear materials for national security and non-proliferation purposes. Due to the substantially lower cross sections at these energies than in the resonance energy region above, these measurements were performed using larger passive targets with the same neutron detector array used in the tagged fission setup.

The experimental techniques used to perform the measurements will be discussed, and preliminary results obtained at beam energies from 5-16 MeV will be presented.

This research is supported in part by the US Department of Homeland Security under Grant No. 20CWDARI00035-01-00, the National Nuclear Security Administration under Grant Nos. DE-NA0003887 and DE-NA0004069, and by the US Department of Energy under Grant No. DE-FG02-97ER41033.

Speaker: Forrest Friesen (Duke University / Triangle Universities Nuclear Laboratory)

friesen_nuclear_photonics_2023_post.pdf

3:10 PM Correlation Measurements from Photofission

Nuclear fission plays a role in many applications such as reactor technology and national security as well as several areas of fundamental nuclear physics. Despite its importance, the complexity of the fission process has precluded a comprehensive theoretical description of this process. To better constrain models of fission, there is a need for experimental data on the properties of fission fragments, prompt neutrons, and prompt γ rays, as well as correlations between these particles. To meet this need, we have begun correlation measurements of observables in photon and neutron-induced fission. An alternative approach uses heavy-ion beams to induce fission with virtual photons and/or particle transfer. Experiments in inverse kinematics provide access to exotic systems and a wealth of high-precision data. Our measurements will serve as a benchmark for these new techniques.

We will discuss recent measurements of the photofission of $^{238}$U performed at the High Intensity Gamma-ray Source at the Triangle Universities Nuclear Laboratory. Fission fragments were detected with a position-sensitive twin Frisch-grid ionization chamber, capable of measuring the kinetic energies, masses, and emission angles of the fission fragments. An array of neutron and 𝛾-ray detectors were used to measure prompt particles from fission in coincidence with the fission fragments. Details of the experimental setup, data analysis, and preliminary results will be presented.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Part of this work was supported by the U.S. DOE National Nuclear Security Administration under Grant No. DE-NA0004069-01

Speaker: Ronald Malone (Lawrence Livermore National Laboratory)

RMalone_NP2023_final.pdf

3:30 PM Comparing Fission-Product Yields from Photon-Induced Fission of Pu-240 and Neutron-Induced Fission of Pu-239 as a Function of Incident Energy

The Bohr Hypothesis, one of the most fundamental assumptions in nuclear fission theory, states that the decay of a compound nucleus with a given excitation energy, spin and parity is independent of its formation. Using fission product yields (FPYs) as a sensitive probe, we have performed novel high-precision tests of the combined effects of the entrance channel, spin, and parity on the fission process. Two different reactions were used in a self-consistent manner to produce a compound $^{240}Pu$ nucleus with the same excitation energy: neutron-induced fission of $^{239}Pu$ and photon-induced fission of $^{240}Pu$. The FPYs from these two reactions were measured using quasimonoenergetic neutron beams from the Triangle Universities Nuclear Laboratory’s (TUNL’s) FN tandem Van de Graaff accelerator [1] and quasimonenergetic photon beams from the High Intensity Gamma-ray Source (HI$\gamma$S) facility. An updated comparison of the FPYs from $^{239}Pu\left(n,f\right)$ at En=1.5 and 4.6 MeV with those from $^{240}Pu\left(\gamma,f\right)$ at $E_\gamma=8$ and 11.2 MeV will be presented.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

[1] M.E. Gooden et al., “Energy Dependence of Fission Product Yields from $^{235}$U, $^{238}$U and $^{239}$Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV.” Nuclear Data Sheets 131, 319 (2016).

Speaker: Jack Silano (Lawrence Livermore National Laboratory)

np2023_silano.pptx

3:50 PM On-Line Detection of Radioactive Fission Isotopes Produced by Laser Driven Gamma Rays

The on-going developments in laser acceleration of charged particles and the production of $\gamma$-rays and neutrons as secondary beams with ultra-high fluxes of particles and radiation provide a basis for novel nuclear physics experiments. These fluxes are very short in both space and time and exceed the capabilities of standard particle accelerators by orders of magnitude. They are particularly interesting in the field of nuclear astrophysics, in the medical field as well as in fusion research.

A direct application is the field of laser-driven nuclear physics. A problem to perform nuclear spectroscopy of the products of nuclear excitation are the $\gamma$ flash and the strong electromagnetic pulse generated in the laser acceleration target, which can lead to signal noise or even detector failure. The protection of the nuclear detection system against these effects is especially important for short-lived nuclides. An effective way is to transport the products away from the laser interaction point. We already demonstrated a functional detection setup in a laser-driven nuclear experiment [1] . It was performed at the Petawatt High-Energy Laser for Heavy Ion Experiments (PHELIX) at GSI. By using laser pulses of 0.5 ps duration with energies up to 200 J, proton pulses in excess of $10^{12}$ protons with energies up to 70 MeV were achieved. These pulses were used for proton induced fission of $^{238}U$. In the meantime the production of $\gamma$-rays was improved at the PHELIX facility. Using a near-critical-density foam ultra-intense electron bunches were accelerated exceeding 100 MeV energy [2].

In combination with a converter target we achieved γ-bunches of more than $10^{11}$ photons at 10 to 15 MeV photon energy. Despite the much lower excitation cross-section compared to proton induced fission we observe clear spectra of the 35 second isotope $^{139}Xe$ . The analysis of the data is still on-going.

[1] P. Boller, A. Zylstra, P. Neumayer, L. Bernstein, C. Brabetz, J. Despotopulos, J. Glorius, J. Hellmund, E. A. Henry, J. Hornung, J. Jeet, J. Khuyagbaatar, L. Lens, S. Roeder, T. Stoehlker, A. Yakushev, Y. A. Litvinov, D. Shaughnessy, V. Bagnoud, T. Kuehl, D. H. G. Schneider, First on-line detection of radioactive fission isotopes produced by laser-accelerated protons Scientific Reports 10 (1) doi:10.1038/s41598-020-74045-5
[2] O. N. Rosmej, et al. 2020 Plasma Phys. Control. Fusion 62 115024

Speaker: Thomas Kühl (GSI, Johannes Gutenberg-Universität, Mainz)

KuehlNuclearPhotonics2023.pdf

4:10 PM → 4:30 PM Break

4:30 PM → 6:40 PM Secondary Beam Production I

Convener: Louise Willingale (University of Michigan)

4:30 PM Advances in Laser-driven Neutron Sources and Applications at Osaka University

The evolution of laser and accelerator technologies has taken a new turn, giving rise to a new transdisciplinary field: Nuclear Photonics. Advances in high-intensity laser technologies have made it possible to accelerate electrons in the GeV class and protons close to 100 MeV from a distance of less than 1 mm. In particular, secondary beams such as laser-driven neutron sources (LDNS) are attracting much interest as a promising application of laser particle acceleration.

LDNS is attracting interest for several reasons, including (i) compactness of the source, (ii) short neutron pulses, and (iii) transportability of the laser beam. By reviewing recent activities at ILE, Osaka University, we discuss the characteristics of LDNS in comparison with accelerator-based neutron facilities. In particular, we discuss the potential and limitations of LDNS by showing that neutrons ranging from meV to MeV [1-10] in energy have been produced by LDNS and applied to neutron radiography [2,7,9], neutron spectroscopy [6,10], astrophysics [3,4], and medical science [8].

[1] S. R. Mirfayzi, A. Yogo, Z. Lan et al. Proof-of-Principle Experiment for Laser-Driven Cold Neutron Source, Scientific Reports 10, 20157 (2020).
[2] A. Yogo, S. R. Mirfayzi, Y. Arikawa, et al. Single Shot Radiography by a Bright Source of Laser-Driven Thermal Neutrons and X-rays, Appl. Phys. Express 14, 106001 (2021).
[3] T. Mori, A. Yogo, T. Hayakawa et al. Direct Evaluation of High Neutron Density Environment Using (n, 2n) Reaction Induced by Laser-Driven Neutron Source, Phys. Rev. C 104, 015808 (2021).
[4] T. Mori, A. Yogo, T. Hayakawa et al. Thermal neutron fluence measurement using a cadmium differential method at the laser-driven neutron source, J. Phys. G: Nucl. Part. Phys. 49 065103 (2022).
[5] Z. Lan and A. Yogo Exploring nuclear photonics with a laser driven neutron source, Plasma Phys. Control. Fusion 64 024001 (2022).
[6] Y. Abe, A. Nakao, Y. Arikawa et al. Predictive capability of material screening by fast neutron activation analysis using laser-driven neutron sources, Review of Scientific Instruments 93 093523 (2022)
[7] T. Wei, A. Yogo, T. Hayakawa et al. Non-destructive inspection of water or high-pressure hydrogen gas in metal pipes by the flash of neutrons and x rays generated by laser, AIP Advances 12, 045220 (2022);
[8] T. Mori, A. Yogo, Y. Arikawa et al. Feasibility study of laser-driven neutron sources for pharmaceutical applications, High Power Laser Sci. Eng., 11, e20 (2023).
[9] Y. Arikawa, A. Morace, Y. Abe et al. Demonstration of efficient relativistic electron acceleration by surface plasmonics with sequential target processing using high repetition lasers, Phys. Rev. Research 5 013062 (2023).
[10] A. Yogo, Z. Lan, Y. Arikawa et al. Laser-Driven Neutron Generation Realizing Single-Shot Resonance Spectroscopy, Phys. Rev. X 13 011011 (2023).

Speaker: Akifumi Yogo (Institute of Laser Engineering, Osaka University)

NP2023_yogo-indico.pdf

5:05 PM Fast neutron generation with few cycle laser pulses

Generation of neutrons from laser-based sources has been the focus of research and development for over two decades. The first step towards generating fusion neutrons is to accelerate ions with sufficient kinetic energy to overcome the repulsive Coulomb potential. So far, most of the ion acceleration experiments have been carried out using multi-cycle, Joule-class lasers. Although the number of neutrons produced in a single laser shot is high, the low repetition rate of such lasers results in a modest average neutron yield (number of neutrons per second) from these systems.

Most of the applications, including nuclear resonance spectroscopy, neutron imaging, isotope production, and transmutation of minor actinides in spent nuclear waste, require a (quasi) continuous source of neutrons operating in a 24/7 mode. Recent developments of few-cycle laser systems with an average optical power of 100 W have laid the technological basis for the development of such a neutron source.

Upon our experimental series conduced at ELI-ALPS in Hungary, first we have demonstrated that ions can be accelerated efficiently with laser pulses of few 10’s mJ energy and few-optical cycle pulse duration [1]. Next, ultrathin deuterated foil targets were fixed to a rotating wheel target system, so that deuterons were accelerated at 1Hz repetition rate in burst of 75 shots. The accelerated deuterons generate neutrons via DD fusion reaction in a deuterated PE tablet. The energy and spatial distribution of the fast neutron beam were characterized by a Time-of-flight (ToF) neutron detector system. The experimental data, comprising more than 3000 laser shots, shows that the neutron conversion efficiency (number of neutron / laser Joule) from our few-optical cycle laser is comparable to that of PW class lasers [2].

Most recently, with the development of an ultrathin liquid sheet target system, it become possible to operate the laser deuteron accelerator continuously for more than six hours at 10 Hz repetition rate. The neutron flux well exceeded 10$^5$ neutron / sec, confirmed by a bubble detector system, too. In a further step, the kHz repetition rate SYLOS laser is to be used, so that a laboratory sized, laser-based neutron source of 10$^7$ – 10$^8$ neutron / second will be available.

This research is supported by the National Research, Development, and Innovation Office of Hungary through the National Laboratory program (contract # NKFIH-877-2/2020, NKFIH-476-4/2021).

[1] S. Ter-Avetisyan et al., “Ion acceleration with few cycle laser pulses” PPCF 65, 085012 (2023).
[2] K. Osvay et al., “Fast neutron generation with few-cycle, relativistic laser pulses at 1 Hz repetition rate,” Sci.Rep., submitted

Speaker: Karoly Osvay (NLTL, University of Szeged)

Osvay_Few cycle_neutron_NP23_230912_pub.pdf

5:40 PM Direct laser acceleration driven ultra-bright gamma and particle radiation sources and applications

Ultra-intense and well collimated gamma and particle beams in the Mega-electronvolt range are of interest for many applications in fundamental research as well as medical and technical applications. For example, in inertial confinement fusion (ICF) and in general nuclear fusion research, diagnostic tools are needed which allows to investigate as well as control plasma processes. Laser induced bright and well collimated short pulse photon and particle radiation sources are capable for such applications.

We present an efficient approach for providing gamma and particle beams based on enhanced production of direct laser-accelerated (DLA) electrons in relativistic laser pulse interactions with a long-scale near critical density plasma at $10^{19}\:W/cm^2$ laser intensity. Our experiments on the interaction of relativistic laser pulses with pre-ionized polymer foam target systems at hundreds Terawatt scale lasers showed a greatly improved conversion of laser energy into energy of Mega-electronenvolts gamma and particle radiation [1-3]. Recent improved experiments have shown the generation of ultra-bright and well-collimated gamma beams with laser energy to gamma conversion efficiency of more than 2% above 10 MeV gamma energy. Furthermore, we could demonstrate the generation of an ultra-intense neutron source with more than $6\times10^{10}$ neutrons per shot with a record laser energy to neutrons conversion efficiency of 0.05%, already at moderate relativistic laser intensities $\left(10^{19}\:W/cm^{2};20\:J\right)$ and ps pulse duration.

Here, I will talk about our results on ultra-intense and bright laser driven radiation sources (especially gamma and neutron sources) provided in interactions of relativistic laser pulses with pre-ionized nanostructured polymer foams. In general nanostructured targets play an important role for providing enhanced particle and improved plasma condition for applications.

The presented results on DLA based laser driven radiation sources such as neutron and gamma beam generation were performed in experiments under the affiliations GSI (Darmstadt, Germany) and Goethe-University (Frankfurt/Main, Germany). The presentation of future concepts and applications of laser induced secondary sources is supported by Marvel Fusion (Munich, Germany).

[1] M. M. Günther et al., “Forward-looking insights in laser-generated ultra-intense gamma-ray and neutron sources for nuclear applications and science”, Nature Communications, 13, 170 (2022).
[2] O. N. Rosmej et al, “Bright betatron radiation from directlaser-accelerated electrons at moderate relativistic laser intensity”, Matter and Radiation at Extremes, 6, 048401 (2021).
[3] P. Tavana et al. “Ultra-high efficiency bremsstrahlung production in the interaction of direct laser-accelerated electrons with high-Z material”, Frontiers in Physics, 11, 1178967 (2023).

Speaker: Marc Guenther (Marvel Fusion GmbH)

6:10 PM Creation of super-high-flux photo-neutrons and gamma-rays > 8 MeV using a petawatt laser to irradiate high-Z solid targets

We report the creation of super-high-flux gamma-rays with energy >8 MeV and photo-neutrons via the ($\gamma$,n) reaction near giant dipole resonance energies (8 - 20 MeV), using the ~130 J Texas Petawatt laser to irradiate high-Z (Au, Pt, Re, W) targets of mm - cm thickness, at laser intensities up to ~5x10$^{21}$ W/cm$^2$ . We detected up to ~ several x 10$^{12}$ gamma-rays >8 MeV (~3% of incident laser energy) and ~ 10$^{10}$ photo-neutrons per shot. Due to the short pulse duration and narrow gamma-ray cone (~17$^o$ half-width) around laser forward, the peak emergent gamma-ray flux >8 MeV reached~10$^{27}$ gammas/cm$^2$ /sec, and the peak emergent neutron flux reached ~10$^{20}$ neutrons/cm$^2$ /sec [1]. Such intense gamma-ray and neutron fluxes will facilitate the study of nuclear reactions requiring super-high-flux of gamma-rays or neutrons, such as the creation of r-process elements. These results may also have far-reaching applications for nuclear energy, such as the transmutation of nuclear waste.

This research is supported by DOE DE-SC0021327 at Rice University.

[1] E. Liang et. al. arXiv:2302.06766

Speaker: Edison Liang (Rice University)

NP23talk.pdf

6:40 PM → 6:50 PM Announcements

Convener: Calvin Howell (Duke University and TUNL)

7:00 PM → 8:30 PM Poster: Poster Session and Reception

7:00 PM P1: Studies of Resonant Compton Scattering for Future

The interaction between photons and electrons is a well-studied phenomenon known as Compton scattering. Based on this mechanism, Compton light sources operating in the x-ray and gamma-ray regions have been developed by colliding a laser beam with an electron beam. One such example is the High-Intensity Gamma Source (HI$\gamma$S) at Triangle Universities Nuclear Laboratory (TUNL). Resonant interaction between photons and atomic systems, such as hydrogen-like ions, has orders of magnitude higher cross-section compared to the electron-photon interaction. Recently, researchers have proposed the Gamma Factory initiative at CERN to take advantage of ultra-relativistic stripped ion beams to generate an intense gamma-ray beam with unprecedentedly high flux. In this work, we will present a simple semi-classical model of a damped-driven oscillator to describe the behavior of resonant Compton scattering. We will discuss the underlying physics of very large resonant total scattering and a few limitations associated with resonant behavior, such as the energy-matching conditions and efficiency of beam-beam scattering. We will also present a framework to develop a simulation code for resonant Compton Scattering.

This work is partially supported by DOE Grant No. DE-FG02-97ER41033.

Speaker: Will Delooze (Duke University and TUNL)

Poster_RCS_Delooze.pdf

7:02 PM P2: Developing Feedback for Rotatable Gamma-beam Linear Polarization for Nuclear Physics Research

The polarization of the gamma-ray beam plays a critical role in experimental photonuclear research by probing angular momentum. For example, the $^{80}$Se(g,n)$^{79}$Se differential reaction cross-section can be measured as a function of the azimuthal angle relative to the plane of polarization. This provides information about the electromagnetic multipolarities involved in the reaction. [1] Dynamic control over gamma beam polarization will open new opportunities in nuclear research, particularly by allowing relative asymmetries to be calculated without the uncertainty introduced by relative detector efficiency. A gamma-ray beam with rotational linear poarization and high polarization purity (Plin ~ .99) has been demonstrated at the High Intensity Gamma-ray Source (HIGS) [2]. Without active tuning by an accelerator physicist, polarization quality is degraded due to decoupling of the free-electron laser (FEL) axis and the electron beam orbit. We are developing an active feedback system that is sensitive to the small centroid motions of the FEL optical axis. Preliminary measurements of the FEL response matrix have been conducted, showing good sensitivity to cavity mirror adjustments. Ongoing work will utilize this feedback system to automatically sustain controllable gamma-ray polarization for nuclear physics experiments.

This research is supported in part by the U.S. Department of Energy under grant no. DE-FG02-97ER41033.

[1] Yates, S.A. et al., “Measurement of the $^{80}$Se(γ,n) reaction with linearly polarized γ rays” Physical Review C, 98, 054621 (2018).
[2] Yan, J. et al., “Precision control of gamma-ray polarization using a crossed helical undulator free-electron laser”, Nature Photonics, 13, 629-635 (2019).

Speaker: Stephen Yates (UNC-CH and TUNL)

Updated Poster for Nuclear Photonics Conference.pdf

7:03 PM P3: Nuclear resonance fluorescence of Pu-242

The nuclear resonance fluorescence (NRF) method was used to study the electromagnetic dipole response of $^{242}$Pu at the superconducting Darmstadt linear electron accelerator S-DALINAC. Monoenergetic electrons with an energy of 3.7 MeV were used to produce bremsstrahlung to irradiate the PuO$_2$ sample with a total mass of about 1 g. The target was highly enriched in the isotope $^{242}$Pu and kept in a special target container due to its total radioactivity of about 370 MBq. Resonantly scattered photons were detected with two high-purity Germanium detectors placed at angles of 90° and 130° relative to the direction of the incident photon beam. NRF spectra of an empty target container, gamma-ray spectra of the sample’s radioactivity and background measurements were taken into account to identify NRF signals of the sample. Gamma rays from the decays of photo-excited states of $^{242}$Pu were observed - making $^{242}$Pu the heaviest nuclide for which NRF information on excited states is available for the moment. Details of the experiment will be described, γ-ray spectra presented and preliminary results discussed.

We thank the Institute of Resource Ecology of HZDR for providing the $^{242}$Pu-sample. This work has been supported by the State of Hesse under the grant ’Nuclear Photonics’ within the LOEWE program.

Speaker: Maike Beuschlein

242Pu_poster_Beuschlein.pdf

7:04 PM P4: Resonant X-ray excitation of the nuclear clock isomer Sc-45

Frequencies are the physical quantity that can be measured with highest precision with applications ranging from clock transitions over search for dark matter to high precision measurements and tests of fundamental constants. Currently, the most precise clock transitions are optical transitions [1]. However, there are also a few nuclear transitions featuring Q-factors on a similar level or even exceeding those of current optical clock transitions. While it may be more challenging to excite these nuclear transitions, they are less sensitive to environmental perturbations caused by electric or magnetic fields. Hence, the interest in nuclear clock transitions, especially Mössbauer transitions, has grown over the last years. Besides $^{229}$Th with its comparably low transition energy of ~8eV [2], one of the most promising candidates for a nuclear clock is the Mössbauer isotope $^{45}$Sc, which has a transition energy of 12.4keV and a natural lifetime of 460ms featuring a Q-factor of ~10$^{19}$. Because of these extreme properties, a direct excitation, which is necessary for applications, only recently became feasible with the advent of high-rep-rate hard x-ray self-seeded free electron lasers. Especially the pulse structure of European XFEL ideally matches the lifetime of the transition. Here, we report on the resonant x-ray excitation of the $^{45}$Sc isomeric state [3]. Our measurements were able to decrease the uncertainty of the transition energy to sub-eV level, which is two orders of magnitude smaller than previously known.

This research is supported in part by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract DE-AC02-06CH11357 and by the National Science Foundation grant No. PHY-2012194.

[1] A. D. Ludlow et al., “Optical atomic clocks”, Rev. Mod. Phys. 87, 637 (2015)
[2] B. Seiferle et al., “Energy of the 229Th nuclear clock transition”, Quantum Sci. Technol.
6, 034002 (2021).
[3] Y. Shvyd’ko et al., “Resonant X-ray excitation of the nuclear clock isomer 45Sc”,
submitted (2023)

Speaker: Miriam Gerharz (Max-Planack-Institut für Kernphysik)

MiriamGerharz_NuclearPhotonics2023.pdf

7:05 PM P5: The isovector spin-M1 response of Zr-90 and Mo-92

For the N=50 isotones $^{90}$Zr and $^{92}$Mo, additional isovector spin-flip M1 (IVSM1) strength could be expected for $^{92}$Mo in comparison to $^{90}$Zr because of the two additional protons in the proton g$_{9/2}$ orbital above the closed pf shell. In addition, the IVSM1 resonance is closely related to Gamow-Teller strengths and can serve to constrain the calculation of electron-capture rates in core-collapse supernova scenarios [1]. Using the newly available hybrid array of HPGe Clover and LaBr$_3$ detectors at the High-Intensity γ-ray source (HIγS), we probed the dipole response of both isotopes in an integral-spectroscopy approach below neutron separation thresholds. The E1 and M1 strengths will be determined up to about 9 MeV by measuring the asymmetries resulting from the excitation of the target nuclei by the fully
polarized γ-ray beam. The experimental method and first results will be discussed.

This work has been supported by DFG Project No.279384907-SFB 1245 and the U.S. DOE Grant No. DE-FG02-97ER41041 and DE-FG02-97ER41033.

[1] K. Langanke et al., Rep. Prog. Phys. 066301 (2021).

Speaker: Amrita Gupta (TU Darmstadt)

AG_NuclearPhotonics_Poster_Printing_new.pdf

7:06 PM P6: Simulation Study on Pinhole Imaging using Nuclear Resonance Fluorescence

Nuclear resonance fluorescence has significant potential in the identification and measurement of isotopes due to its specificity for different nuclei. This study explored the NRF pinhole imaging technique through Monte Carlo simulations in the detection of $^{239}$Pu samples. By designing and optimizing key parameters of the pinhole imaging system, including the direction of incident photons, geometric aperture, acceptance angle, pinhole thickness, object distance and magnification factor, high spatial resolution of 1.2cm with good signal-to-noise ratio of 1.63 have been achieved. Simulation results preliminarily demonstrate the capability of NRF pinhole imaging to effectively distinguish $^{239}$Pu samples with different concentrations and sizes and obtain direct imaging results without the need for further data processing. However, challenges such as high-energy noise photons and low count rate of NRF photons limit the image quality. Further investigations are warranted to develop imaging correction algorithms that can compensate for these effects and enhance the accuracy of NRF pinhole imaging.

[1] Vavrek, J.R., Henderson B.S., Dnaagoulian A. Experimental demonstration of an isotope-sensitive warhead verification technique using nuclear resonance fluorescence[J]. Proceedings of the National Academy of Sciences - PNAS, 2018. 15(17): p. 4363-4368.
[2] Hayakawa T., Kikuzawa N., Hajima R., et al. Nondestructive assay of plutonium and minor actinide in spent fuel using nuclear resonance fluorescence with laser Compton scattering[J]. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers,Detectors and Associated Equipment, 2010, 621(1-3): 695-700.
[3] Bertozzi W, Ledoux R.J.. Nuclear resonance fluorescence imaging in non-intrusive cargo inspection[J]. Nuclear Instruments and Methods in Physics Research B, 2005, 241: 820-825.
[4] Kikuzawa N., Hajima R., Nishimori N., et al. Nondestructive Detection of Heavily Shielded Materials by Using Nuclear Resonance Fluorescence with a Laser-Compton Scattering γ-ray Source[J]. Applied Physics Express, 2009, 2: 36502.
[5] Shizuma T., Hayakawa T., Hajima R., et al. Nondestructive identification of isotopes using nuclear resonance fluorescence[J]. Review of Scientific Instruments, 2012, 83(1): 015103.
[6] Daito I., Ohgaki H.,Suliman G. , et al. Simulation Study on Computer Tomography Imaging of Nuclear Distribution by Quasi Monoenergetic Gamma Rays with Nuclear Resonance Fluorescence[J]. Energy Procedia, 2016, 89: 389-394.
[7] Ali K., Ohgaki H., Zen HS, et al. Selective Isotope CT Imaging Based on Nuclear Resonance Fluorescence Transmission Method[J]. IEEE transactions on nuclear science, 2020, 67(8): p. 1976-1984.
[8] Toyokawa H., Ohgaki H.,Hayakawa T., et al. Two-Dimensional Isotope Imaging of Radiation Shielded Materials Using Nuclear Resonance Fluorescence[J]. Janpanses Journal of Applied Physics, 2011, 50(100209):1-5.
[9] Hajima R., Hayakawa T., Kikuzawa N., et al. Proposal of nondestructive radionuclide assay using a high-flux gamma-ray source and nuclear resonance fluorescence[J]. Journal of Nuclear Science and Technology, 2008, 45(5):441-451.
[10] Gamma Beam Industrial Applications at ELI-NP, Technical Design Report, in press.
[11] Hagmann C.A., Hall J.M., Johnson M.S., et al. Transmission-based detection of nuclides with nuclear resonance fluorescence using a quasimonoenergetic photon source[J]. Journal of Applied Physics, 2009. 106(8):084901-084901-7.
[12] Jordan, D.V. and Warren G.A.. Simulation of nuclear resonance fluorescence in Geant4[J]. IEEE Nuclear Science Symposium Conference Record, 2007,7:1185-1190.
[13] Quiter, BJ. Nuclear Resonance Fluorescence for Nuclear Materials Assay[J].UC Berkeley Electronic Theses and Dissertations, 2010.
[14] Löcker M, Fischer P, Krimmel S, et al. Single Photon Counting X-Ray Imaging with Si and CdTe Single Chip Pixel Detectors and Multichip Pixel Modules. IEEE Transactions on Nuclear Science,2004,51(4):1717-1723.
[15] Smith, M.F. and R.J. Jaszczak, An analytic model of pinhole aperture penetration for 3D pinhole SPECT image reconstruction. Physics in medicine and biology, 1998. 43(4).
[16] Habraken, J.B., et al., Evaluation of high-resolution pinhole SPECT using a small rotating animal. Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2001. 42(12).
[17] Smith M.F., Jaszczak R.J., Wang H. Pinhole aperture design for 131I tumor imaging[J]. IEEE Transactions on Nuclear Science, 1997, 44(3):1154-1160
[18] Mattews S.M. A pinhole for producing a close in image of an extended 14 MeV neutron source[R]. UCRL-51860,1975.
[19] Paix, D., Pinhole imaging of gamma rays. Physics in medicine and biology, 1967. 12(4).
[20] Hsieh SS, Leng S, Yu L, Huber NR, McCollough CH. A minimum SNR criterion for computed tomography object detection in the projection domain. Med Phys. 2022 Aug;49(8):4988-4998. doi: 10.1002/mp.15832. Epub 2022 Jul 10. PMID: 35754205; PMCID: PMC9446706.
[21] ANGER H O. Radioisotope cameras in instrumentation in nuclear medicine: Vol. 1[M]. New York: Academic, 1967: 485-552.
[22] van der HAVE F, BEEKMAN F J. Penetration, scatter and sensitivity in channel micro-pinholes for SPECT: A Monte Carlo investigation[J]. IEEE Trans Nucl Sci, 2006, 53: 2 635-2 645.
[23] Dai QS. Analytical Design Method of Pinhole Collimator for High -Energy γ Photon Imaging[J]. Atomic energy science and technology，2010,9(44):631-635.
[24] Calin Alexandru Ur; Gamma beam system at ELI-NP. AIP Conference Proceedings 24 February 2015; 1645 (1): 237–245.
[25] Wang H, Jaszczak R.J., Coleman R.E. Monte Carlo modeling of penetration effect for Iodine-131 pinhole imaging[J]. IEEE Transactions on Nuclear Science, 1996, 43(6):3272-3277

Speaker: Lin Jin (Tsinghua University)

7:07 PM P7: Measurement of Prompt Neutron Spectra from Photofission of U-235, U-238, and Pu-239

Energy spectra for prompt neutrons emitted from actinide targets irradiated with $\gamma$-ray beams have been measured near the ($\gamma$, n) reaction threshold by Mueller et al. [1]. Examples of measurements of the total cross sections for prompt neutron emission from photofission and neutron multiplicities as a function of the incident $\gamma$-ray beam energy are reported by [2, 3]. The most recent neutron energy and angle double differential yields for prompt neutron emission from photofission were reported by Clark et al. [4]. Their measurements were performed using $\gamma$-rays produced in the beam stop of a neutron spallation source and therefore had a broad energy spread. We are performing the first double differential yield measurements of prompt neutrons emitted from photofission induced with a monoenergetic $\gamma$-ray beam. This work is made possible by the beam features at HIGS, e.g., monoenergetic, pulsed and circularly polarized.

In this study, we aim to expand measurements of prompt photoneutron spectra to include data taken on the low and high energy sides of the Giant Dipole Region (GDR). The experimental technique is based on tagging fission events using fission chambers as active targets. Neutrons are detected with wide angle coverage in our new "Soccer Ball" array which consists of at most thirty 12.70 cm (diameter) x 5.08 cm (thick) liquid scintillators distributed around the target. The pulsed $\gamma$-ray beam at HIGS enable the neutron energy to be determined with time-of-flight measurements using the accelerator RF signal. To determine the differential neutron multiplicity, timing coincidences between the fission chambers and neutron detectors are utilized. The experimental techniques and preliminary results will be presented.

This research is supported in part by [U. S. Department of Energy Grant numbers DE-NA0003887 and DE-NA0004069, Lawrence Livermore National Security, LLC under contract number DE-AC52-07NA27344, and Los Alamos National Nuclear Security, LLC under contract 89233218CNA000001].

[1] J. M. Mueller et al. Measurement of prompt neutron polarization asymmetries in photofission of $^{235,238U, 239}$Pu, and $^{232}$Th. Phys. Rev. C 85, 014605 (2012).
[2] S. Nair et al. Fission-neutron and fragment angular distributions from threshold photofission of $^{232}$Th and $^{238}$U. J. Phys. G: Nucl. Phys. 3, 965 (1977).
[3] A. Lengyel et al. Energy dependent prompt neutron multiplicity parameterization for actinide photofission. arXiv:1801.01107 [nucl-th] (2018).
[4] S. D. Clarke et al. Measurement of the energy and multiplicity distributions of neutrons from the photofission of $^{235}$U. Phys. Rev. C 95, 064612 (2017).
[5] J. T. Caldwell et al. Experimental Determination of Photofission Neutron Multiplicities for $^{235}$U, $^{236}$U, $^{238}$U, and $^{232}$Th Using Monoenergetic Photons. Nucl. Sci. Eng. 73, 153 (1980).

Speaker: Ethan Mancil (Duke University / Triangle Universities Nuclear Laboratory)

EAM Poster 9-5-23 NP Final.pdf

7:08 PM P8: Measurement of Energy Spectrum of Delayed Neutrons from Photon-Induced Fission

The time distribution and energy spectra of the delayed neutrons emitted from fission
provide information about the excitation energies of the fission fragments and reveal structure properties of the fragments. In addition, detection of delayed neutrons and γ-rays provide clean signatures for identifying fissile materials in γ-ray beam-based cargo scanners. Accurate prompt and delayed particle emission data for photon-induced fission are essential for developing technologies for assaying nuclear devices based on remote interrogation techniques using γ-ray beams. Optimum use of the probe γ-ray beam involves detection and analysis of the energy spectra of the γ-rays and neutrons emitted from γ-ray induced nuclear reactions on the container and its contents. This work focuses on the delayed neutrons from photofission of actinide nuclei. We are measuring the first double differential (time and energy) distributions of the delayed neutrons emitted in photon-induced fission using a mono-energetic γ-ray beam. These measurements are performed at the High Intensity Gamma-ray Source (HIγS) at TUNL using a circularly polarized beam in the energy range of 6 to 10 MeV. The energy spectra of the delayed neutrons are measured using $^3$He ionization detectors. This presentation will describe the GEANT-4 modeling of the neutron detection in
the $^3$He ionization chambers.

• This research is supported in part by the U.S. Department of Homeland Security (DHS), Countering Weapons of Mass Destruction (CWMD) Academic Research Initiative (ARI) under grant no. 20CWDARI00035-01-00 and by the U.S. Department of Energy under grant nos. DE-FG02-97ER41033 and DE-SC0005367.

Speaker: Courtney Martin (NCCU | TUNL)

7:09 PM P9: Energy-dependence of the γ-decay branching ratio of the Giant Dipole Resonances of Sm-154 and Ce-140

The giant dipole resonance (GDR) is a fundamental nuclear excitation that dominates the dipole response of all nuclei. The present work aims at quantifying the branching ratio of the decay of the GDR of $^{154}$Sm and $^{140}$Ce, via emission of γ-rays or neutrons as a function of excitation energy. Simultaneously to a nuclear resonance fluorescence (NRF) measurement an activation measurement has been performed at the HIγS facility. By determining the activation of these targets and then comparing to the GDR-NRF events that are observed, we will determine the γ-to neutron-decay branching ratio. The data, their analysis and first results will be presented and discussed.

This work is supported by the LOEWE program under grant Nuclear Photonics and within the Hessian cluster project ELEMENTS.

Speaker: Kiriaki Prifti (Technische Universität Darmstadt)

7:10 PM P10: Gamma-ray phase contrast imaging studies based on VIGAS

With the rapid development of advanced manufacturing industries, there is a great demand for high-resolution imaging methods applicable for metal materials in the field of nondestructive testing (NDT). Due to the large focal spot and broad spectrum characteristics of a bremsstrahlung-based gamma-ray source, the resolution of the traditional absorption-based gamma-ray imaging method is limited to the submillimeter level, which cannot meet the urgent requirement of high-resolution imaging for metal materials in NDT. Hence, it is necessary to develop novel gamma-ray imaging modalities for this application.

Using the phase shift information of an imaging object, the phase contrast imaging (PCI) has been proved to be an excellent imaging method for low Z materials in the X-ray energy since the phase-shift cross-section is about 2-3 orders higher than the absorption cross-section. Our preliminary study shows that the PCI also has advantages for metal material imaging in the gamma-ray region, since a maximum cross-section ratio between the phase-shift and the absorption can be obtained for metal materials in the MeV energy region. Meanwhile, the intrinsic edge enhancement characteristics in in-line PCI can help to discriminate the material interfaces, which can be used to identify the holes, cracks, etc. Hence, gamma-ray PCI provides a novel way for high-resolution imaging for metal materials.

To realize gamma-ray PCI, the prerequisite is a gamma-ray source characterized by high spatial coherence. The advent of an inverse Compton scattering (ICS) light source, based on the interaction of relativistic electrons and high-intensity laser, provides an excellent prospect for the gamma-ray PCI, since it can provide quasi-monochromatic, energy tunable, high brightness, and high coherent gamma-rays.

To demonstrate the feasibility of gamma-ray PCI, we have developed a simulation method of gamma-ray PCI for metal samples based on the very compact ICS gamma-ray source (VIGAS) facility under construction in Tsinghua University, which is designed to provide quasi-monochromatic gamma-rays in the 0.2 – 4.8 MeV energy region for advanced radiation imaging applications [1]. The effects of finite focal spot, energy dispersion, and other physical properties of the VIGAS are considered in the simulation. Using the simulation method, a phantom of concentric tungsten–aluminum spheres is simulated. Compared to conventional absorption imaging, clear edge enhancement is witnessed in the PCI image, which will facilitate the identification of the material interface. The simulation results prove the feasibility of gamma-ray PCI for metal samples.

This research is supported in part by the National Natural Science Foundation of China (No. 12027902).

[1] J.Y. Sun, Z.J. Chi, Y.C. Du, R.K. Li, W.H. Huang, C.X. Tang, A simulation method of gamma-ray phase contrast imaging for metal samples, Nucl. Instrum. Methods Phys. Res. A 1053 (2023) 168321.

Speaker: Jiayi Sun (Tsinghua University)

posterV3.pdf

7:11 PM P11: Flat-laser Compton Scattering Gamma-ray Beam for Multi-isotope CT Imaging in UVSOR-III

A flat distribution in the energy spectrum and a spatial distribution with a small beam size, Flat-Laser Compton Scattering Gamma-ray (F-LCS) beam, has been generated by exciting a circular motion of an electron beam for a multi-isotope CT Imaging application through Nuclear Resonance Fluorescence (NRF) method. A proof-of-principle experiment to generate F-LCS beam has been carried out at the beamline BL1U in UVSOR-III where a helical undulator is installed. The electron beam with 746 MeV and about 6 mA collided head-on with the laser beam from a Tm-fiber laser system (TLR-50-AC-Y14, IPG Laser GmbH) with around 1 W CW power. A high-purity germanium detector with a relative efficiency of 120% was used to measure the energy spectra of the generated gamma-rays for different K-value of the helical undulator from 0 to 0.3. Using a 2-mm collimator placed about 8.7 m downstream of the center of BL1U, the energy bandwidth of the standard LCS beam (K=0) was 2.7% FWHM. When we excited the undulator K=0.2, the energy bandwidth became wider, 7.2% FWHM. At the same time, the peak energy shifted from 5.53 MeV to 5.50 MeV. These results showed a good agreement with EGS5 simulation [1]. We also measured the F-LCS beam's space distribution and obtained reasonable results.

Next, we tried to take a multi-isotope imaging by using F-LCS beam in UVSOR. The F-LCS beam with K=0.2 irradiated $^{206,207,208}$Pb enriched targets simultaneously and NRF peaks from all three isotopes were observed. The yields of the F-LCS excited NRF peaks below 5300 keV were larger than those by the standard LCS beam, which was consistent with the ratio of the energy spectrum of the F-LCS beam to the standard LCS beams.

This research is partially supported by the Japanese Sociality for the Promotion of Science (JSPS) KAKENHI under Grants 21H01859 and 22H01239. This experimental work was performed at the BL1U of UVSOR Synchrotron Radiation Facility with the approval of Institute for Molecular Science (IMS), National Institute of Natural Science (NINS) (Proposal No. 21-603, 21-806, 22IMS6605, 22IMS6806, 23IMS6607).

[1] H. Ohgaki et al., “GENERATION OF FLAT-LASER COMPTON SCATTERING GAMMA-RAY BEAM IN UVSOR,” Proc. of 13th Int. Particle Acc. Conf, 3070, (2022).

Speaker: Shinya Tanizaki (Kyoto University)

NP2023 tanizaki.pdf

7:12 PM P12: Measurements of short-lived fission products from photon-induced fission of U-238

Photon-induced fission product yield (FPY) studies were conducted on 238 U. Fission was induced at the Triangle Universities Nuclear Laboratory’s High Intensity γ-ray Source using monoenergetic γ-rays of Eγ = 8.0, 9.8, 11.2, 13.0, and 15.5 MeV. The FPYs of short-lived isotopes were measured using a RApid Belt-driven Irradiated Target Transfer System (RABITTS). The RABITTS is a fully automated 1-m track system which performs cyclic activation by moving the target between irradiation and counting positions. Following γ-ray beam irradiation, the target was rapidly transferred (in 0.4 s) to the counting position located at the midpoint between two well-shielded High Purity Germanium detectors, which measure the γ-ray energy spectrum associated with the decay of the induced activity. The irradiation-counting cycle was repeated until the summed data have sufficient statistical precision. The counting data were used to validate the half-lives of the fission products. More than 30 fission products with half-lives ranging from 1 s to 600 s were uniquely identified, and their yield values determined.

This work was supported in part by the National Nuclear Security Administration Stewardship Science Academic Alliances grant no. DE-NA0003887, DE-NA0004069, and the U.S. Department of Energy, Office of Nuclear Physics, under grant no. DE-FG02-97ER41033. This work was also partially supported by the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 by Los Alamos National Laboratory under Contract No. 89233218CNA000001.

Speaker: Innocent Tsorxe (Duke University and TUNL)

7:13 PM P13: Nucleon Polarizabilities and Elastic Compton Scattering on He-3 at HI𝜸S

The electric and magnetic polarizabilities ( 𝛼$_{𝐸1}$ and 𝛽$_{𝑀1}$ ) are fundamental quantities encoding the internal structure of nucleons. They characterize the response of the nucleon to an external electromagnetic field and can be probed using Compton scattering processes. From chiral effective field theories ( 𝜒 EFTs) [1,2], the angular distributions of the Compton differential cross section for light nuclei (A=1-6) provide an important way of extracting the nucleon electromagnetic polarizabilities experimentally. However, due to the difficulties in experimental measurements, 𝛼$_{𝐸1}$ and 𝛽$_{𝑀1}$ of nucleons, particularly of the neutron, are still not precisely determined [3-5].

Compton scattering measurements using a liquid He-3 target are planned for determining neutron electromagnetic polarizabilities. These measurements will be carried out using the nearly monoenergetic gamma-ray beam at the High Intensity Gamma-Ray Source (HI𝛾S) facility at Triangle Universities Nuclear Laboratory (TUNL). This experiment will be the first Compton-scattering measurement performed on He-3 , mainly because of limitations of cryogenic techniques, which have been recently overcome. Compared to Compton Scattering experiments on liquid deuterium [6] and He-4 [7,8], the elastic Compton cross section of He-3 arises from a different combination of the nucleon contributions. This can provide another way to extract the polarizabilities of the neutron and another test under the EFT formalism [9], although nuclear effects need to be taken into account. The proposed experiment will measure the angular differential cross section for Compton scattering from He-3 at 100 MeV using a circularly polarized photon beam at HI𝛾S. In this poster, we will present the techniques and proposed setup of this experiment as well as theoretical predictions for the sensitivity to the polarizability in the angular distribution of the cross section.

This research is supported by the U.S. Department of Energy under Contracts DE-FG02-03ER41231, DE-SC0016581, DE-SC0005367, DE-FG02-97ER41033, DE-SC0016656, and National Science Foundation 2232117.

[1] H. W. Griesshammer, J. A. McGovern, D. R. Phillips and G. Feldman, Prog. Part. Nucl. Phys. 67, 841 (2012);
[2] H.W. Griesshammer, J.A. McGovern and D.R. Phillips, invited talk at the 8th International Workshop on Chiral Dynamics (Pisa, Italy, June 2015);
[3] J. A. McGovern, D. R. Phillips and H. W. Griesshammer, Eur. Phys. J. A 49,12 2013);
[4] L. S. Myers et al. [COMPTON@MAX-lab], Phys. Rev. Lett. 113, no.26, 262506 (2014);
[5] L. S. Myers et al. Phys. Rev. C 92, no.2, 025203 (2015);
[6] D. Godagama, PhD Dissertation, DOI: 10.13023/etd.2022.281 (2022);
[7] M. Sikora et al. (Compton@HIGS Collaboration), Phys. Rev. C96, 055209 (2017);
[8] X. Li et al.(Compton@HIGS Collaboration), Phys. Rev. C 101, 034618 (2020);
[9] A. Margaryan, B. Strandberg, H.W. Griesshammer, J.A. McGovern, D.R. Phillips and D. Shukla, Eur. Phys. J. A54, 125 (2018)

Speaker: Jingyi Zhou (Duke University)

Compton_poster_NuclearPhotonic2023.pdf

7:14 PM P14: Average Current Enhancement of Laser-Plasma Accelerators

Since they have been proposed, laser-plasma accelerators have interested the scientific community for their ability to generate electric fields exceeding the ones of Linacs and RF cavities. Several efforts have been made in order to produce monochromatic electron beams and to increase their maximum energy, often at the expense of the charge. However, some applications like femtosecond chemistry, radio-biology and industrial radiography do not need monochromatic beams, but rather highly charged ones (i.e., > 1 nC). For some of these applications it is also necessary to reduce the amount of high energy electrons (i.e., > 10 MeV), in order to avoid the activation of materials. Such beams can be produced using high Z gases like Nitrogen and Argon[1,2].

Here we numerically[3] and experimentally investigate this little-known regime, employing different laser energies, f-numbers and plasma densities. This allowed us to find the conditions to produce electron beams with charges up to tens of nC and exceeding 100 mrad in divergence. We will also show and explain the dependencies of these beams (e.g., their charges and energy spectra) as functions of the aforementioned laser and plasma parameters.

This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement n°101020100.

[1] J. Götzfried et al. (2020) Physics of nanocoulomb-class electron beams in laser-plasma wakefields, arXiv.
[2] J. Feng et al. (2022) Laser plasma accelerated ultra-intense electron beam for efficiently exciting nuclear isomers, arXiv.
[3] Rémi Lehe et al. (June 2016) A spectral, quasi-cylindrical and dispersion-free Particle-In-Cell algorithm, Computer Physics Communications.

Speaker: Lorenzo Martelli (Thales-MIS & IP-Paris)

7:15 PM P15: HPGe-BGO Pair Spectrometer for ELI-NP

The new European research facility called ELI-NP (Extreme Light Infrastructure - Nuclear Physics) is being built in Bucharest-Magurele, Romania. ELI-NP will offer unprecedented opportunities for photonuclear reactions with high intensity, brilliant and fully polarized photon beams at energies up to 19.5 MeV.

The 8 HPGe CLOVER detectors of ELIADE are important instruments for the γ-spectroscopic study of photonuclear reactions. We investigate the possibility to operate an advanced version of an anti-Compton shield (AC shield) as escape γ-rays pair spectrometer for one of the ELIADE CLOVERS. This should improve the performance at high energies where the pair production process dominates. The BGO shield operated as a stand-alone device can also be used as γ-beam intensity monitor and to investigate the cross section for pair production near the threshold.

A prototype pair spectrometer, consisting of 64 BGO crystals with SiPM (silicon photomultiplier) readout, has been designed and built. Two test measurements with high energy photons have been performed at the University of Cologne and at the ILL in Grenoble. Results are going to be presented.

This work is supported by the German BMBF (05P15RDENA) and the LOEWE-Forschungsschwerpunkt “Nuclear Photonics”.

Speaker: Ilja Homm

NP2023.pdf

7:16 PM P16: Nuclear Thermometer using Single Pulse of Laser-driven Neutron Source

Neutron resonance diagnosis technology has been developed worldwide for several decades. Most previous studies have used neutrons provided by large-scale particle accelerators. As a new approach to neutron generation, the Laser-Driven Neutron Source (LDNS) has been studied to obtain neutron pulses with the ultra-short pulse duration and high flux[1]. By setting a converter at downstream of the laser-accelerated ion source, the high energy ions generate neutrons with an yield up to ~10$^{11}$ within 1 ns via nuclear reactions such as $^9$Be(p, n)$^9$B and $^9$Be(d, n)$^{10}$B. By adding a moderator to the secondary target, the neutrons can be moderated to epithermal or lower energy (meV~eV), providing a new probability to achieve neutron resonance diagnosis with higher accuracy and smaller space. Therefore, many applications such as neutron imaging[2,3], radioactive experiments[4] and resonance spectroscopy[5] can be realized by LDNS.

In the experiment, the petawatt laser LFEX was used to shot a CD foil target as an ion acceleration source, and a cylindrical beryllium encased by a high-density polyethylene (HDP) moderator was used as the neutron source and moderator. We set a neutron beamline of 1.8m to measure the neutron resonance peaks around 4.28eV of a Ta plate which was heated to different temperatures to give an experimental evidence of isotope-discriminating nuclear thermometer using a single shot of LDNS. The experimental results and discussions will be introduced in the presentation.

This work was funded by Grant-in-Aid for Scientific Research (No. 25420911, No. 26246043, and No. 22H02007) of MEXT, A-STEP (AS2721002c), and PRESTO (JPMJPR15PD) commissioned by JST.

[1] Zechen Lan et al Plasma Phys. Control. Fusion 64 (2022) 024001
[2] Akifumi Yogo et al Appl. Phys. Express 14 106001 (2021)
[3] Tianyun Wei et al AIP Advances 12, 045220 (2022)
[4] Takato Mori et al PHYSICAL REVIEW C 104, 015808 (2021)
[5] Akifumi Yogo et al, PHYSICAL REVIEW X 13, 011011 (2023)

Speaker: Zechen Lan (Institute of Laser Engineering, Osaka University, Japan)

NP2023_Lan_poster.pdf

Wednesday, September 13

7:30 AM → 8:30 AM Breakfest

8:30 AM → 8:45 AM Announcements

Convener: Calvin Howell (Duke University and TUNL)

8:45 AM → 10:25 AM Secondary Beam Production II and LC Sources

Convener: Dan Stutman (ELI-NP)

8:45 AM Production of energetic electrons, protons and neutrons with the PETAL and APOLLON PW lasers

The different types of energetic particle sources generated by PetaWatt (PW) lasers can serve for various applications in many research fields, including nuclear physics. In this presentation, we will report on recent numerical and experimental results on particle acceleration as well as neutron generation with the (~ 0.3 kJ, 0.6-1 ps, 5×10$^{18}$ Wcm$^{-2}$) PETAL and (~ 45 J, 20 fs, 10$^{22}$ Wcm$^{-2}$) Apollon laser systems.

First, we will address electron acceleration by means of the PETAL beam interacting with a gas jet of ~10$^{19}$ cm$^{-3}$ density in the self-modulated laser wakefield regime. Multidimensional particle-in-cell simulations, performed for various gas densities and lengths, foresee the generation of electron beams with energies as high as ~ 300 MeV and charge up to 100 nC. These predictions have been confirmed, as we will show, by a first experiment conducted on the LMJ-PETAL facility.

Second, we will examine, through PIC and Monte Carlo simulations, the laser acceleration of protons from thin-foil or double-layer targets and their subsequent conversion into neutrons in secondary LiF and lead targets. This setup has been investigated using both the PETAL and Apollon laser parameters. Our simulations indicate that, compared to PETAL, the more intense, tightly focused Apollon beam should produce a lower number of protons but with higher energies, so that a similar number of fast neutrons should be released from the secondary conversion target. This is also what we observe in experiments we performed both at Apollon (where up to 55 MeV protons and ~10$^8$ MeV-range neutrons were produced) and PETAL (30 MeV protons, and > 10$^9$ fast neutrons depending on the laser and converter parameters); in both cases, results reasonably agree with these predictions.

Overall, the above results open encouraging perspectives for laser-based nuclear physics studies on PW-class facilities.

Speaker: Xavier Davoine (CEA DAM DIF)

pres_NP2023_XDavoine.pdf

9:20 AM Demonstration for Cu-67 production with neutrons provided from laser

Recent progress in laser physics enabled us to generate high-flux particle pulses by laser-plasma interactions with high power laser. One of the possible applications for laser-driven beams from a compact laser system is generation of medical radioisotopes inside of hospitals. At present, many medical radioisotopes have been produced by compact proton accelerators or nuclear reactors. However, some candidates for new medical radioisotopes cannot be produced by these methods because of the lack of suitable stable isotopes as the nuclear reaction target.

We have proposed production of a medical radioisotope $^{67}$Cu using $^{67}$Zn(n, p)$^{67}$Cu and $^{68}$Zn(n, pn)$^{67}$Cu reactions with fast neutrons provided from laser-driven neutron sources (LDNSs). $^{67}$Cu-pharmaceutical is a candidate for medical diagnostic scans by gamma-rays and cancer therapy by beta-ray, but production method has not been established. Protons and deuterons were accelerated by laser-plasma interactions, and subsequently neutrons were generated by the p+$^9$Be and d+$^9$Be reactions. We measured gamma-rays from neutron irradiated samples using Ge detectors after a laser shot. We obtained the yield of (3.3±0.5)×10$^5$ atoms for $^{67}$Cu, corresponding to a radioactivity of 1.0±0.2 Bq, with a single laser shot. Using a simulation based on this result, we estimated $^{67}$Cu production with a high-frequency laser. The result suggests that it is possible to generate $^{67}$Cu with a radioactivity of 270 MBq using a future laser system with a frequency of 10 Hz and 10000-s radiation in a hospital [1].

[1] T. Mori, et al. “Feasibility study of laser-driven neutron sources for pharmaceutical applications”, High Power Laser Sci. Eng., 11, e20 (2023).

Speaker: Takehito Hayakawa (National Institutes for Quantum Science and Technology)

laser_neutron_medical_RI4.pdf

9:55 AM Combination of a Diffraction Based Ultra-Narrow Band Width Filter with a Laser Compton Photon Source

We report on an effort to create a flexible ultra-narrow, bandwidth (10$^{-5}$ to 10$^{-6}$), high-energy (100 keV to 3 MeV) photon source consisting of a high spectral density Laser Compton Source (LCS) and an ultra-high precision crystal diffractometer. We explain design choices allowing the construction of a LCS with high photon phase space density and pronounced energy-angle correlation. We further demonstrate the realization of a mobile crystal diffractometer with sub-nanoradian angular resolution. The combination of both devices allows to enhance the application space substantially. We explain how to tune center energy and how to narrow the bandwidth down to the intrinsic natural width of nuclear resonances. These capabilities allow to optimize band width for isotope sensitive inspection of materials based on nuclear resonance fluorescence and absorption at large distance from the sample without any spectroscopic capability of the detection system and independent of the time structure of the LCS source. Further we demonstrate options of high energy beam manipulation (focusing, beam steering, dual energy beams) using the combination of an LCS with the crystal diffractometer. In the last part we highlight a few applications of this setup for battery research and nuclear fuel material inspection.

This research is supported in part by the U.S. Department of Defense under DARPA grant HR00112090059.

Speaker: Michael Jentschel (Institut Laue-Langevin)

10:25 AM → 11:00 AM Break

11:00 AM → 12:30 PM Nuclear Astrophysics

Convener: Akaa Ayangeakaa (University of North Carolina at Chapel Hill / TUNL)

11:00 AM Experimental Studies of Gamma-Induced Reactions for the P-Process

The source of a series of rare, proton-rich stable isotopes, known as the p nuclei, remains an open question in nuclear astrophysics. The p nuclei cannot be produced through the known neutron capture processes such as the s and r process, but instead are thought to be synthesized in astrophysical environments where a series of photodisintegration reactions on s-process seeds takes place. Various sites have been proposed for the production of p-process nuclei, such as type Ia supernovae or neutrino-driven winds from core collapse supernovae. A major source of uncertainty in understanding the production of p nuclei is the necessity to use cross sections and reaction rates derived from theoretical models, in particular the statistical Hauser-Feshbach approach. With very little experimental constraint, these cross section predictions can vary by orders of magnitude, preventing a careful assessment of the conditions needed to produce p nuclei in the abundances observed today.

To tackle the need for experimental constraint of the predicted cross sections, the HI$\gamma$S P-Process Collaboration has undertaken several measurements of gamma-induced charged-particle emission of p-process nuclei across the range of energies relevant to explosive supernova environments. By utilizing an array of highly-segmented, high resolution silicon detectors, the energy and angle of the outgoing protons and alphas produced via the photodisintegration reactions from monoenergetic beams of gamma rays at HI$\gamma$S can be measured, and the total and partial cross sections derived and compared to predictions. In this talk, the experimental setup, preliminary analysis, and future plans will be discussed.

This research is supported in part by the U.S. Department of Energy under grant nos. DE-AC05-00OR22725 and the Romanian Ministry of Research, Innovation and Digitalization under project no. PN-III-P4-PCE-2021- 1024 and PN 23 21 01 06.

Speaker: Kelly Chipps (Oak Ridge National Laboratory)

We2.01.Chipps.web.pdf

11:35 AM Nuclear Astrophysics Studied With TPCs Operating in Gamma-Beams

Measurements of cross section and their extrapolation to stellar conditions are now routinely performed with accuracy of 5% or better. But the formation of $^{16}$O in the fusion of helium with $^{12}$C, in the $^{12}$C($\alpha,\gamma$) $^{16}$O reaction, is still not known with sufficient accuracy, in spite of the central role that this reaction plays in stellar evolution theory. The Warsaw-UConn-SHUBU-ELINP collaboration, developed a new method to measure this cross section by measuring with (mono-energetic) gamma-beams the inverse process of the photo-dissociation of $^{16}$O to $^{12}$C and an alpha-particle. The measurements are performed at the HIgS facility using TPC detectors [1,2] operating with CO$_2$ gas, hence also serving as an active target TPC (AT-TPC).

We will discuss initial measurements with an optical readout TPC (O-TPC) [1] that demonstrated the viability of our method [3] and recent results obtained in 2022 [4], with an electronic readout TPC detector (eTPC) [2]. Briefly, the UConn-TUNL (2012) measurement with an O-TPC allowed us to bench mark the measurement with a TPC against the world data on the $^{12}$C($\alpha,\gamma$) reaction [3], as well as to demonstrate viable measurements of angular distribution over the entire 0º-180º angular range. The recent Warsaw-UConn-SHU-BUELINP measurement [4], with the considerably improved Warsaw-TPC detector, including 1,024 channels of electronic readout, allowed for an energy scan with nominal energies E$\gamma$ = 13.9 MeV to 8.51 MeV (nominal Ecm = 1.35 MeV) [5], to be presented here. Automated data analyses with an application of machine learning technology [5,6] is in progress. We intend (PAC 2023 approved LOI) to continue with measurements at the HI$\gamma$S at lower energies, with the anticipated beam intensity in excess of 109 $\gamma/s$ inside the TPC.

Supported in part by the U.S. Department of Energy grant no. DE-FG02-94ER40870 and National Science Centre, Poland, contract no. 2019/33/B/ST2/02176.

[1] M. Gai, M.W. Ahmed, S.C. Stave, W.R. Zimmerman, A. Breskin, B. Bromberger, R. Chechik, V. Dangendorf, Th. Delbar, R.H. France III, S.S. Henshaw, T.J. Kading, P.P.
Martel, J.E.R. McDonald, P.-N. Seo, K. Tittelmeier, H.R. Weller, and A.H. Young. JINST 5, 12004 (2010).
[2] M. Ćwiok, M. Bieda, J.S. Bihałowicz, W. Dominik, Z. Janas, Ł. Janiak, J. Manczak, T. Matulewicz, C. Mazzocchi, M. Pfützner, P. Podlaski, S. Sharma, M. Zaremba, D. Balabanski, A. Bey, D.G. Ghita, O. Tesileanu, M. Gai, Acta. Phys. Pol. B 49, 509 (2018).
[3] R. Smith, M. Gai, S. R. Stern, D. K. Schweitzer, M. W. Ahmed, Nature Communications 12, 5920 (2021).
[4] M. Ćwiok, W. Dominik, A. Fijałkowska, M. Fila, Z. Janas, A. Kalinowski, K. Kierzkowski,
M. Kuich, Ch. Mazzocchi, W. Okliński, M. Zaremba, M. Gai, D.K. Schweitzer, S.R. Stern,
S. Finch, U. Friman-Gayer, S.R. Johnson, T. Kowalewski, D.L. Balabanski, C. Matei, A.
Rotaru, K.C.Z. Haverson, R. Smith, R.A.M. Allen, M.R. Griffiths, S. Pirrie, and P.S.R
Alcibia, EPJ Web Conf. 279, 04002 (2023),
[5] Mikołaj Ćwiok et al., contribution to this conference, Nuclear Photonics 2023.
[6] Robin Smith et al., contribution to this conference, Nuclear Photonics 2023.

Speakers: Moshe Gai (University of Connecticut), Wojciech Dominik

nuclear_photonics_2023_WD.pdf

12:10 PM Photo-disintegration of O-16 at astrophysical energies studied with the Warsaw TPC at the HIγS facility

An active-target time-projection chamber (TPC) was developed by the University of Warsaw, in collaboration with University of Connecticut and ELI-NP/IFIN-HH, to measure nuclear reactions of astrophysical interest[1,2]. The experimental program focuses on the study in the laboratory ($\gamma$,p) and ($\gamma$,$\alpha$) reactions which are the time reversal of (p,$\gamma$) and ($\alpha$,$\gamma$) that regulate nucleosynthesis in stars. In particular, the benchmark reaction is $^{12}$C($\alpha$,$\gamma$)$^{16}$O, which regulates the carbon-to-oxygen ratio.

The methodology takes advantage of high-intensity monochromatic and collimated gamma beams available today at the High Intensity Gamma-Ray Source (HI$\gamma$S) facility, TUNL, Durham, NC, USA. The employed active-target TPC technique is characterized by a 4p solid angle coverage, which allows to reconstruct in 3D the momenta and angular distributions of the charged reaction products of photo-disintegration reactions. Different reactions can be studied by tuning composition and density of the gaseous target for particular energy of the gamma beam.

In 2022 two experimental campaigns were carried out to study $^{16}$O and $^{12}$C photodisintegration reactions using low-pressure CO$_2$ gas target and monochromatic gamma-ray beams produced at the HI$\gamma$S facility with beam energies ranged from 13.9 MeV down to 8.51 MeV (i.e., nominal center-of-mass energies from 6.7 MeV down to 1.35 MeV, respectively). In the presentation I will discuss detector design, methods of track reconstruction, in-situ detector energy scale calibration and highlights from preliminary results. The prospects for future measurements at energies down to 1 MeV in the center-of-mass will be given.

[1] M. Kuich et al., “Active target TPC for study of photonuclear reactions at astrophysical energies,” Acta Phys. Pol. B, Proc. Suppl., 16, 4-A17 (2023).
[2] M. Ćwiok et al., “Studies of photo-nuclear reactions at astrophysical energies with an active-target TPC,” EPJ Web of Conferences, 279, 04002 (2023).

Speaker: Mikolaj Cwiok (Faculty of Physics, University of Warsaw)

cwiok_slides_NP2023_v5.pdf

12:30 PM → 2:00 PM Conference Photo followed by Lunch

2:00 PM → 4:20 PM Laser-Driven Charged-Particle Acceleration

Convener: Chad Forrest (Laboratory for Laser Energetics (LLE), University of Rochester)

2:00 PM Advancing Nuclear Fusion Energy: Focused Energy’s Approach to Proton Fast Ignition and Laser-Driven Radiation Sources

Focused Energy, startup founded in July 2021, is dedicated to commercializing nuclear fusion energy using the proton fast ignition approach. As part of our pathway towards fusion energy, we leverage the technologies developed and employ laser-driven radiation sources as an early spin-off technology to provide further benefits to society. This presentation will elaborate our approach on laser-driven inertial confinement fusion and emphasize why we think the best way to inertial fusion energy is using the direct drive method with proton fast ignition.

Additionally, we will outline our strategic plans for facility development, which play a crucial role in advancing our fusion energy objectives. These plans encompass the creation of a compression physics test platform, a powerplant technology demonstrator, and a fusion power plant prototype. These facilities will serve as invaluable tools for comprehensive experimentation, enabling us to refine our concepts, validate our hypotheses, and bring us closer to the practical implementation of fusion energy.

In addition to our fusion energy endeavors, we will showcase our utilization of laser technology to create industrialized laser-driven radiation sources. Specifically, we will highlight our work in developing the first dedicated laser-driven neutron source in Darmstadt. This facility, equipped with a 20 J 100 Hz laser, has the potential to generate over 10$^{11}$ neutrons per second, revolutionizing industrial applications such as non-destructive characterization and material analysis. We will present recent results of demonstrations of laser-driven neutron resonance spectroscopy, neutron radiography [1] and hard x-ray radiography and highlight upcoming future developments and potential applications.

This research is supported in part by the LOEWE Center for Nuclear Photonics and the state of Hesse.

[1] Zimmer, Marc, et al. "Demonstration of non-destructive and isotope-sensitive material analysis using a short-pulsed laser-driven epi-thermal neutron source." Nature Communications 13.1 (2022): 1173.

Speaker: Marc Zimmer (Focused Energy GmbH)

2:30 PM Recent developments of the OMEGA tritium beam platform for studying light ion nuclear reactions

In a recent benchmarking experiment, a tritium beam was generated via the target normal sheath acceleration (TNSA) mechanism using tritiated titanium targets. These targets were irradiated with an on-target intensity of 2x10$^{18}$ W/cm$^2$ with the high-energy (1250-kJ), short-pulse (10-ps) OMEGA EP laser. The energy spectrum of the beam was found to exponentially decrease with a high-energy cutoff at ~10 MeV, containing ~10$^{12}$ tritons per pulse, comparable to other TNSA experiments with protons. In a second experiment, the tritium beam was directed onto a secondary deuterated-polyethylene target, which produced 10$^8$ neutrons from DT fusion nuclear reactions. However, studying reactions with lower cross-sections requires a substantial yield increase to obtain meaningful neutron spectra. While independent radiological measurements of the targets confirm that enough tritium is available for acceleration, proton contaminants lower the tritium acceleration efficiency. Therefore, a new experimental series has been scheduled on OMEGA-EP to investigate if the targets can be cleaned using a suitable laser pre-pulse. Preliminary experimental data and future applications of the tritium beam will be discussed.

This work was supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856.

Speaker: Arnold Schwemmlein (University of Rochester)

Schwemmlein Nuclear Photonics 2023.pdf

2:50 PM Research on medical applications of high power lasers at ELI-NP

The potential of high-power (TW to multi-PW) lasers for high societal impact medical applications has been anticipated from the beginnings of the field about two decades ago. Since then, progress in the high power laser research, as well as the development of the first platforms for preclinical studies, have strongly strengthened the case for medical applications. A far reaching research program has been recently developed at ELI-NP, aiming to investigate three major medical applications of high power lasers. Radiotherapy with laser accelerated heavy ions, such as carbon, may allow more patients to benefit from this most advanced cancer treatment modality, now accessible only to the richest countries. In addition, the ultrarapid dose delivery possible with lasers may give the revolutionary capability to spare the healthy tissues during tumor treatment (FLASH effect [1]). Laser produced X-ray sources may enable implementing in clinics and hospitals advanced phase contrast-based imaging modalities, such as high sensitivity low dose mammography, or high precision image guidance in radiotherapy [2,3]. Lastly, laser-based production of medical radioisotopes may enable more affordable and widespread use of nuclear medicine diagnostic and treatment modalities [4].

The medically oriented research at ELI-NP will also guide the development of future laser-based medical diagnostic and treatment facilities. In particular, a pilot research Center on medical applications of high power lasers is envisioned at ELI-NP, aiming to take the results of the above research towards the preclinical and, in the long term, even clinical testing stage. The motivation and foundation for high power laser-based medical applications, the ELI-NP research plans, and first preparatory results will be presented.

This work is carried out under the contract PN 23 21 01 06 sponsored by the Romanian Ministry of Research, Innovation, and Digitalization; supported by ELI-NP project—Phase II, co-financed by the Romanian Government and the European Union through the European Regional Development Fund: the Competitiveness Operational Program (1/07.07.2016, C.O.P., ID 1334); by the Impulse (Integrated Management and Reliable Operations for User-based Laser Scientific Excellence) project -H2020 project no. 871161, and by the M-ERANET project 'NiWRe Alloys'.

[1] Asavei, T., Bobeica, M., Nastasa, V., Manda, G., Naftanaila, F., Bratu, O., Mischianu, D., Cernaianu, M.O., Ghenuche, P., Savu, D., Stutman, D., Tanaka, K.A., Radu, M., Doria, D. and Vasos, P.R. (2019), Laser-driven radiation: Biomarkers for molecular imaging of high dose-rate effects, Med. Phys., 46: e726-e734
[2] N. Safca, D Stutman, E Anghel, F Negoita and C A Ur, 2022 Phys. Med. Biol. 67, 23NT01
[3] Stutman, D., N. Safca, P. Tomassini, E. Anghel, and C. A. Ur, Towards high-sensitivity and low-dose medical imaging with laser x-ray sources, in Compact Radiation Sources from EUV to Gamma-rays: Development and Applications, vol. 12582, 35-46. SPIE, 2023
[4] A. S. Cucoanes, D. L. Balabanski, F. Canova, P. Cuong, F. Negoita, F. Puicea, and K. A. Tanaka, On the potential of laser driven isotope generation at ELI-NP for positron emission tomography, Proc. SPIE 10239, Medical Applications of Laser-Generated Beams of Particles IV: Review of Progress and Strategies for the Future, 102390B (7 June 2017)

Speaker: Dan Stutman (ELI-NP)

Nuclear Photonics Stutman final.pdf

3:20 PM Laser production of medical isotopes Cu-62, 64 and Ga-68 and nuclear isomer Mo-93m and its astrophysical implication on Mo-92 production

Radioisotopes are indispensable agents in medical diagnosis and treatment, among which copper-62, 64 (Cu-62, 64) and gallium-68 (Ga-68) are medical isotopes widely used in positron emission tomography imaging. Nuclear isomer Mo-93m has a (21/2)$^+$ isomer at 2,425 keV with a half-life of 6.85 h and a (17/2)$^+$ intermediate state that lies 4.85 keV higher at 2,430 keV with a half-life of 3.5 ns. Such isomeric property is attractive to exploiting the depletion of nuclear isomers via nuclear excitation by electron capture. Experimental study of these radioisotopes and nuclear isomer have gained a lot attention. Recently, experiments that generate these radioisotopes and isomer via laser-induced nuclear reactions were performed on the XingGuangIII laser facility of the Laser Fusion Research Center in Mianyang. In this presentation, we introduce experimental study on laser production of Cu-62, 64, Ga-68, and Mo-93m using the XingGuangIII laser facility. Their respectively production yields were obtained to be of the order of 10$^6$ per laser shot. The prospect of producing the medical isotopes Cu-62,64 and Ga-68 are further evaluated using a table-top femtosecond laser system of high repetition. In addition, the effect of nuclear reaction flow on the population of $^{93m}$Mo is studied. The $^{93m}$Mo involved photodisintegration reactions leading to the production of $%^{92}$Mo, which is one of the most debated p-nuclei, is further discussed. It is found that the $^{93}$Nb(p, n)$^{93m}$Mo reaction is an important production path for $^{93m}$Mo seed nucleus, and the influence of $^{93m}$Mo-$^{92}$Mo reaction flow cannot be ignored.

This research is supported by the National Key R&D Program of China (Grant No. 2022YFA1603300) and the National Natural Science Foundation of China (Grant No. U2230133)

Speaker: Wen Luo (University of South China)

Wen Luo—Laser production of medical isotopes Cu-62, 64 and Ga-68 and nuclear isomer Mo-93m using XingGuangIII laser facility.pdf

3:40 PM Tight Focusing in Air of a mJ-class Femtosecond Laser: A Radiation Safety Issue

Shielding for ionizing radiation is a critical safety measure for experiments performed with Joule-class lasers and this is becoming increasingly important for mJ-class lasers, especially at high average power. In-air experimental configurations of laser-generated radiation require further radiation safety considerations as the simpler implementation can lead to an even higher exposure risk. We present a straightforward method to generate MeV-ranged electron beams in ambient air through the tight focusing (NA $\cong$ 1) of a 12 fs, 3 mJ, infrared laser (λ$_0$ = 1.8 μm) operating at 100 Hz [1]. The measured dose rates range from 15 μGy/min at 6 m and up to 9 Gy/min at 0.1 m from the interaction zone. For reference, conventional radiation therapy for cancer treatments is typically performed at dose rates < 6 Gy/min. For an exposed researcher positioned at 1 m from the source, the delivered dose exceeds the public dose limit of 1 mGy/year (for electrons and x-rays), set by the Canadian Nuclear Safety Commission (CNSC) [2], in less than one second and warrants the implementation of radiation protection. We therefore advise to use high caution for researchers performing tight-focusing in air with mJ-class femtosecond lasers.

We show that relativistic peak intensities in ambient air are enabled by a very low B-integral from the use of a 1.8 μm central wavelength, a few-cycle pulse duration and a tight focusing geometry which altogether push further the intensity clamping limit. This generates a near-critical plasma in ambient air leading to a strong laser-to-electron energy conversion efficiency that explains the measured high dose rates. Three-dimensional Particle-In-Cell simulations confirm that the acceleration mechanism is based on the relativistic ponderomotive force and show theoretical agreement with the measured electron energies and divergence. Finally, we discuss the scalability of this method with the continuing development of high average power mJ-class lasers. This technique provides a promising approach for FLASH radiation therapy.

This work is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), Compute Canada and Fonds de Recherche du Québec - Nature et Technologies (FRQNT).

[1] S. Vallières et al., "High Dose-Rate Ionizing Radiation Source from Tight Focusing in Air of a mJ-class Femtosecond Laser", arXiv, DOI:10.48550/arXiv.2207.05773 (2022).
[2] Nuclear Safety and Control Act, ”Radiation Protection Regulations”, Canadian Nuclear Safety Commission, URL: https://laws-lois.justice.gc.ca/eng/regulations/SOR-2000-203/FullText.html

Speaker: Simon Vallières (Institut national de la recherche scientifique (INRS))

NuclearPhotonics2023_SVallieres.pdf

4:00 PM Quasi-mono energetic deuteron acceleration by in-direct laser shot

Laser power has increased into petawatt since the introduce of CPA, leading to many new fields including laser driven ion acceleration. Ions such as protons and deuterons can be accelerated into Multi-MeV by high power laser [1], leading to some applications such as compact neutron source [2,3], proton radiography [4]. For some further applications such as cancer therapy, researchers are trying to increase the ion max energy [4] and narrowing the ion energy width [5] both in experiments and theories. Several acceleration mechanisms by laser-target direct interaction have been reported, some of them indicate that ion beam with narrow energy width could be obtained, but they are experimentally difficult due to the strict requirements of laser and target conditions.

Here, we report an in-direct method which can obtain quasi-mono energetic deuteron beam easily in experiments. The experiments are conducted at ILE, Osaka University. A primary target (Al) is focused by LFEX laser, and electrons and protons are accelerated from it. A secondary target (heavy water capsule) is set at the normal direction after the primary target. By optimizing the experiment conditions such as the distance of the 2 targets and the size of the heavy water capsule, deuterons over 10 MeV with energy width less than 1 MeV can be accelerated from the capsule. The acceleration experiment details and its possible application to D-D neutron source will be discussed in the presentation.

[1] A. Yogo, et al. "Boosting laser-ion acceleration with multi-picosecond pulses." Scientific reports 7.1 (2017): 42451.
[2] A. Yogo, et al. "Laser-driven neutron generation realizing single-shot resonance
spectroscopy." Physical Review X 13.1 (2023): 011011.
[3] T. Wei, et al. "Non-destructive inspection of water or high-pressure hydrogen gas in metal pipes by the flash of neutrons and x rays generated by laser." AIP Advances 12.4 (2022):045220.
[4] B. Shi, et al. "Picosecond snapshot imaging of electric fields induced on a cone guide target designed for fast ignition scenario." Journal of Plasma Physics 88.4 (2022): 905880404.
[5] A Higginson, et al. "Near-100 MeV protons via a laser-driven transparency-enhanced hybrid acceleration scheme." Nature communications 9.1 (2018): 724.
[6] A. V. Brantov, et al. "Quasi-mono-energetic ion acceleration from a homogeneous composite target by an intense laser pulse." Physics of plasmas 13.12 (2006): 122705.

Speaker: Tianyun Wei (LIE, Osaka University)

np2023ーwei.pdf

4:20 PM → 4:30 PM Announcements

Convener: Calvin Howell (Duke University and TUNL)

4:30 PM → 5:00 PM Break

6:35 PM → 9:35 PM Durham Bulls Game

Thursday, September 14

7:30 AM → 8:30 AM Breakfest

8:30 AM → 8:45 AM Announcements

Convener: Calvin Howell (Duke University and TUNL)

8:45 AM → 10:30 AM Photonuclear Reactions

Convener: Kelly Chipps (Oak Ridge National Laboratory)

8:45 AM Electric dipole response of exotic nuclei studied by virtual photon scattering

The electric dipole response of nuclei is dominated by the collective excitation mode known as the giant dipole resonance. This resonance accounts for most of the electric dipole strength and can be interpreted as a harmonic oscillation of protons against neutrons. However, a question arises when considering the addition of extra neutrons to nuclei: How does this impact the dipole response?

To address this question, extensive studies have been conducted to investigate the dipole response of exotic nuclei through virtual photon scattering experiments. Experimental evidence demonstrates the presence of significant dipole strength near the neutron threshold in neutron halo nuclei, where the last neutron is weakly bound. This strength is attributed to the non-resonant excitation of a weakly bound neutron into continuum. In medium-heavy neutron-rich nuclei characterized by relatively high neutron separation energy, a distinct dipole strength known as the pygmy dipole resonance (PDR) emerges at an excitation energy of 6 to 10 MeV. Despite the comprehensive investigations, the nature of the PDR remains uncertain.

In this contribution, we present an experimental methodology for probing the electric dipole response using virtual photon scattering, along with the responses observed in various neutron-rich nuclei. Furthermore, we discuss the evolution of the PDR across the Calcium isotope chain, incorporating our most recent experimental findings.

This research is supported in part by JSPS Grant-in-Aid for Scientific Research Grants No. JP21H01114.

Speaker: Yasuhiro Togano (RIKEN Nishina Center)

NuclearPhotonics2023_Submit.pdf

9:20 AM Discrepancies between (p,p’) and (γ,xn) experiments

High energy-resolution proton inelastic scattering experiments with E$_p$ = 200 MeV were performed on the even-even Nd isotope chain and $^{152}$Sm. The relativistic Coulomb excitation experiments focused on the excitation-energy region of the IsoVector Giant Dipole Resonance (IVGDR) and made use of the zero-degree mode of the K600 magnetic spectrometer at iThemba LABS. A goal of the highlighted study was to confirm the K-splitting observed in previous photo-absorption measurements at Saclay. The comparison of the shape of the IVGDR in the transition from spherical to deformed nuclei yielded significant discrepancies between equivalent photo-absorption cross sections obtained from the K600 data and the photo-absorption data obtained at Saclay. In addition, discrepancies have also been observed between photo-absorption data taken at the Saclay and Livermore laboratories. These discrepancies will be discussed along with future investigations into the possible reasons for them.

Speaker: Lindsay Donaldson (iThemba Labs, National Research Foundation)

9:50 AM The Temperature-dependent Relative Self-Absorption technique

One of the fundamental properties of excited nuclear quantum states is their lifetime which is related to the level width. A precise measurement of this width for key-states of light isotopes is of fundamental importance. Level widths and decay strengths are not only important observables for classifying the structure of atomic nuclei, but they can also serve as a crucial test of the modeling of nuclear forces and of nuclear quantum transitions [1]. In particular, transition probabilities in light isotopes can help us understand the importance of 2- and 3-body interactions in the framework of chiral Effective Field Theory and of the role of 2-body currents (2BC) in decay transitions. However, for many isotopes the width of low-lying levels is not measured with a sufficient precision.

A well known technique to obtain lifetimes and level widths in a wide range of energies is the use of Nuclear Resonance Fluorescence (NRF) and Self-Absorption (SA) [2]. In recent years a new technique called Relative Self-Absorption (RSA) has been developed at TU Darmstadt [1, 2]. It has been demonstrated that this technique provides reduced systematic uncertainty for values of the level widths compared to traditional NRF and SA. However, the analysis of the data at this level of precision required already information on the details of the thermal motion of the nuclei of interest in the target, such as the Debye temperature of the material.

In this contribution an advanced RSA technique will be presented, the Temperature-dependent RSA (TRSA), which overcomes the limitations of the RSA related to the pre-existing knowledge of the thermal motion properties of the targets used in the measurement [3]. In TRSA, measurements in multiple target-temperatures, from a 70 K to 500 K, are performed. The Debye temperature of the target materials and the level width of the state of interest are measured simultaneously. The theoretical analysis, which will be presented, shows that this method reduces the systematic uncertainties of the measured transition matrix elements, down to the level of some parts in a thousand, by avoiding systematical uncertainties of theoretical treatments of thermal material properties.

The features of the temperature-control target system which is under developed in the Institute for Nuclear Physics of the Technische Universität Darmstadt will be presented.

This research is supported in part by the State of Hesse within the LOEWE research project “Nuclear Photonics” and the Deutsche Forschungsgemeinschaft – Project-ID 279384907 – SFB 1245.

[1] U. Friman-Gayer et al., Phys. Rev. Lett. 126, 102501 (2021).
[2] A. Zilges, D. Balabanski, J. Isaak, N. Pietralla, Prog. Part. Nucl. Phys. 122, 103903 (2022).
[3] R. Moreh et al. Phys. Rev. B 56, 187 (1997).

Speaker: Norbert Pietralla (TU Darmstadt)

NP23_Koseoglou-webpage.pdf

10:10 AM Theoretical motivations to push for development of polarized gamma-rays experiments in nuclear physics

Despite giant progresses, nuclear structure physics faces a number of challenges, one of which is the role of clusters configurations in the structure of light and medium mass nuclei and the progressive disappearance with growing A of clusters states in favor of single-particle or collective excitations. The relevance of nuclear molecules has been highlighted in various disconnected experiments and theories, dealing with specific nuclei, but not with a campaign covering the lower part of the nuclear chart in full. A systematic search for the effects of irradiating samples with polarized gamma-rays, giving additional information on nuclear structure, should be made.

The availability of tunable polarized gamma-ray sources, coupled with detectors that might analyze the degree of polarization is essential in this endeavor. I will review a few theoretical motivations to carry on experiments with polarized gamma-rays [1,2] as a push to the development of new and sophisticated ways of production and detection of this important probe. In particular, I will focus on the relevance of polarization in the classification of the discrete symmetries that a molecular configuration might take and the relevance in light nuclei, such as well-bound $^{12}C$, $^{16}O$ or more exotic $^{11}Li$ and $^{11}Be$ nuclei.

This research is supported in part by the INFN specific initiative MONSTRE.

[1] L.Fortunato, “Establishing the geometry of α clusters in $^{12}C$ through patterns of polarized γ rays” Phys. Rev. C, 99, 031302(R) (2019).
[2] L.Fortunato, “How to determine the shape of nuclear molecules with polarized gamma-rays”, SciPost Phys. Proc. 3, 035 (2020).

Speaker: Lorenzo Fortunato (Dept. Physics and Astronomy- Univ. Padova (Italy) & INFN-Padova)

Durham-Fortunato-2023.pdf

10:30 AM → 10:50 AM Break

10:50 AM → 12:00 PM High Precision Probe of Nucleon and Nuclear Structure with Photons

Convener: Mohammad Ahmed (North Carolina Central University)

10:50 AM Probing the low-energy electromagnetic response of nucleons using Compton scattering

The fundamental properties of the nucleon reflect the internal dynamics of a composite system. In particular, the application of external electromagnetic fields induces a response in the constituent charge and current distributions in the nucleon, which is reflected in the electromagnetic polarizabilities. Nuclear Compton scattering is an ideal reaction for exploring these effects. While the first-order response to the incident photon is determined by the charge and magnetic moment, the second-order response is given by the static electric and magnetic polarizabilities $\alpha_N$ and $\beta_N$ and of the nucleon, which are structure-dependent. The next highest order effect is parameterized by the spin polarizabilities $\gamma$, which encode the stiffness of the nucleon spin.

High-precision measurements of these observables provide necessary benchmarks of theories describing hadron structure such as Chiral effective field theories and lattice QCD. Knowledge of the polarizabilities helps address the proton radius puzzle through their contributions to the Lamb shift in muonic hydrogen. In addition, the proton-neutron mass difference can be related to the difference in the respective magnetic polarizabilities $\beta_p-\beta_n$.

The High Intensity Gamma-Ray Source (HI$\gamma$S), housed at the Free Electron Laser Laboratory at Duke University, is able to produce intense, quasi-monoenergetic photon beams with nearly 100% circular or linear polarization. These beam characteristics, along with a cryogenic cooling system capable of creating liquid targets of hydrogen, deuterium, and helium, are essential components in performing such measurements. Using these tools, the Compton@HIGS collaboration aims to collect high-statistics Compton scattering data on a series of light nuclei at incident beam energies below pion threshold in order to provide stringent constraints on the scalar polarizabilities of the proton and neutron. To date, data has been collected on $^1$H, $^2$H, and $^4$He, and preparations are underway for a planned measurement on He. The status of these data, along with implications for the polarizabilities, will be discussed.

This research is supported in part by the U.S. Department of Energy under grant no. DE-SC0016581.

Speaker: Mark Sikora (George Washington University)

nucleon_response_sikora.pdf

11:25 AM Study of the Th-229 nuclear clock isomer using X-ray beam

Among thousands of nuclei, the isotope Thorium-229 ($^{229}$Th) is the only nucleus with an excitation level (isomer state) of about 8 eV and has attracted attention as a nucleus that can be excited by a laser. Nuclei are less sensitive to external fields than atoms and can achieve extremely stable quantum states. One promising application is the “nuclear clock”, which could potentially outperform the atomic clock. The isomeric transition could also be utilized for many fields, including fundamental physics and various practical applications.

To excite $^{229}$Th by lasers, detailed information on isomer-level energies, lifetimes, and other related details is needed. In 2016, the existence of the isomer state was confirmed by observing the internal conversion electrons [1]. Since then, many experiments have reported the detailed information on the isomer state [2-5]. In 2023, the first radiative decay from the isomer was observed and its precise energy was reported [6]. It is expected that research will rapidly progress toward the first laser excitation.

Aiming at further study of isomer state in crystals, we have been developing a new method using nuclear resonant scattering with synchrotron radiation X-ray. This "active X-ray pumping" allows us to produce isomer states from the ground state $^{229}$Th in a controllable manner [7]. By utilizing this method to $^{229}$Th-doped CaF$_2$ crystals, we have successfully observed the deexcitation vacuum ultraviolet (VUV) radiation from the isomer. This result leads to the detailed study of isomers in CaF$_2$ crystals.

In this talk, I will discuss our VUV observation. In addition, I will also give an overview
of our XAFS(X-ray Absorption Fine Structure) experiments to probe the electronic state of Th in crystals, which provide important information for manipulating the isomer in the crystals.

[1] L.v.d. Wense et al., “Direct detection of the $^{229}$Th nuclear clock transition”, Nature ,533, 47 (2016)
[2] B. Seiferle et al., “Energy of the $^{229}$Th nuclear clock transition”, Nature, 573, 243 (2019).
[3] J. Thielking et al., “Laser spectroscopic characterization of the nuclear-clock isomer $^{229m}$Th”, Nature 556, 321 (2018).
[4] A. Yamaguchi et al., Energy of the 229Th Nuclear Clock Isomer Determined by Absolute $\gamma$-ray Energy Difference”, Phys. Rev. Lett. 123, 222501
[5] T. Sikorsky et al., “Measurement of the $^{229}$Th Isomer Energy with a Magnetic Microcalorimeter”, Phys. Rev. Lett. 125, 142503 (2020)
[6] S. Kraemer et al., “Observation of the radiative decay of the $^{229}$Th nuclear clock isomer”,Nature 617, 706 (2023)
[7] T. Masuda et al., “X-ray pumping of the Th-229 nuclear clock isomer”, Nature, 573, 238 (2019).

Speaker: Koji Yoshimura (Okayama university)

NP2023_KYoshimura.pdf

12:00 PM → 1:30 PM Lunch

2:00 PM → 6:00 PM Tour: Tour of TUNL Research Facilities

2:00 PM Bus leaves the DCC for HIγS

2:45 PM HIγS tour and visit the Duke Chapel

5:15 PM Bus departs HIγS for the DCC

7:00 PM → 8:30 PM Conference Banquet with live music

Friday, September 15

7:30 AM → 8:30 AM Breakfest

8:30 AM → 8:45 AM Announcements

Convener: Calvin Howell (Duke University and TUNL)

8:45 AM → 10:05 AM Graduate Student Session: Research and Applications with Real Photons

Convener: Prof. Norbert Pietralla (TU Darmstadt)

8:45 AM Investigation of the low-lying dipole response of Ni-64 using real photonscattering experiments

Real photon-scattering experiments are a well-established technique to investigate dipole-excitation modes due to the low angular-momentum transfer of photons [1-3]. On the one hand, the usage of an energetically-continuous $\gamma$-ray beam enables the determination of absolute transition strengths in a broad energy range. On the other hand, $\left(\gamma,\gamma'\right)$ experiments utilizing a quasimonoenergetic and linearly-polarized photon beam allow for the assignment of the radiation’s character to the observed transitions and the investigation of total photoabsorption cross sections. Therefore, the combination of these complementary measurements exhibit the complete study of the dipole response below the particle-separation threshold.

For gaining a better understanding of the different dipole-excitation modes of atomic nuclei, systematic studies using different probes on the same nuclide (multimessenger approach [4]) or using the same probe along, e.g., isotopic and isotonic chains are crucial. For the latter one, the proton-magic nickel isotopic chain (Z = 28), which consists of four even-even, stable isotopes with N/Z ratios between 1.07 and 1.29, is well suited. The dipole response of $^{58,60}Ni$ has already been investigated by analyzing real photon-scattering data [5-7]. In addition, the unstable isotopes $^{68,70}Ni$ were measured in Coulomb-excitation experiments in inverse kinematics for studying the low-lying dipole response [8-10].

One missing link for completing the systematics is the investigation of the most neutron-rich, stable Ni isotope $^{64}Ni$. Hence, both aforementioned types of complementary $\left(\gamma,\gamma'\right)$ experiments were performed on this isotope.

In this contribution, the experiments and first results will be presented.

This research is supported by the BMBF [05P21PKEN9].

[1] A. Zilges et al., PPNP 122, 103903 (2022).
[2] U. Kneissl, H. H. Pitz, A. Zilges, PPNP 37, 349 (1996).
[3] U. Kneissl, N. Pietralla, and A. Zilges, J. Phys. G 32, R217 (2006).
[4] D. Savran et al., Phys. Lett. B 786, 16 (2018).
[5] F. Bauwens et al., Phys. Rev. C 62, 024302 (2000).
[6] M. Scheck et al., Phys. Rev. C 87, 051304(R) (2013).
[7] M. Scheck et al., Phys. Rev. C 88, 044304 (2013).
[8] O. Wieland et al., Phys. Rev. Lett. 102, 092502 (2009).
[9] D.M. Rossi et al., Phys. Rev. Lett. 111, 242503 (2013).
[10] O. Wieland et al., Phys. Rev. C 98, 064313 (2018).

Speaker: Miriam Müscher (University of Cologne)

NP23_Muescher_upload.pdf

9:05 AM Model-independent test of the Brink-Axel hypothesis

The Brink-Axel (BA) hypothesis states that the transition probability between two groups of states, described by the photon strength function (PSF) for a given multipolarity, only depends on the energy difference between the states and not on their intrinsic properties. As a consequence, the upward (absorption/excitation) and downward (emission/deexcitation) PSF are expected to be the same. For $^{96}Mo$, significant discrepancies were found [1] with various experimental probes between upward (bremsstrahlung/$\left(\gamma,\gamma′\right)$) and downward (Oslo-method/$\left(^3He,^3He'\gamma\right), \left(p, p'\right)$) PSF in the energy region of the Pygmy Dipole Resonance.

A new method [2] allows for the simultaneous model-independent measurement of upward and downward PSF in a single $\left(\overrightarrow{\gamma},\:\gamma'\gamma''\right)$ nuclear resonance fluorescence (NRF) experiment using quasi-monochromatic linearly-polarized $\gamma$-ray beams. To study the discrepancies and BA hypothesis, NRF experiments on $^{96}Mo$ were performed at the High Intensity $\gamma$-ray Source $\left( HI\gamma S\right)$ at energies of 3.9 to 9.25 MeV.

In this contribution, first results will be shown and discussed.

Supported by the State of Hesse, grant “Nuclear Photonics” (LOEWE program), the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 279384907 – SFB 1245, and the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under grant nos. DE-FG02-97ER41041 and DE-FG02-97ER41033.

[1] A. Bracco, E. G. Lanza and A. Tamii, Prog. Part. Nucl. Phys. 106, 360 (2019)
[2] J. Isaak et al., Phys. Lett. B 788, 225 (2019)

Speaker: Oliver Papst (Technische Universität Darmstadt)

9:25 AM Nuclear Resonance Fluorescence as a Test of Shell-Model Interactions at High Excitation Energy and Low Spin in Zn-68

The structure of the $^{68}$Zn isotope is investigated using nuclear resonance fluorescence, where low-spin levels were excited using linearly polarized photon beams at energies ranging from 3 MeV to the particle threshold using the High Intensity Gamma-Ray Source. This nucleus is the isotone of $^{66}$Ni where triple shape coexistence has been established recently.
Excited states of interest were cataloged across a broad range of energies. The resulting gamma decay was measured and characterized using an array of high-purity germanium clover detectors and cerium bromide scintillators. Two 40-hour coincidence measurements were performed at beam energies just below the particle threshold to investigate low-lying, low-spin excited states, which are fed by the decay cascades of high-energy states populated directly by the beam. The low-spin gamma-decay data will be used to investigate the structure of $^{68}$Zn in the shell-model picture, comparing the observables, i.e., spin and parity quantum numbers, excitation energies, branching ratios, multipole mixing ratios, and scattering cross section data to the results of calculations using different effective shell-model interactions.

This research is supported in part by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Grants No. DE-FG02-97ER41041 (UNC), No. DE-FG02-97ER41033 (TUNL).

Speaker: Samantha Johnson (UNC Chapel Hill, TUNL)

68ZnNRF_SJohnson_NuclearPhotonics2023.pdf

9:45 AM γ-decay Behavior of the Giant Dipole Resonances of Sm-154 and Ce-140

The giant dipole resonance (GDR) is one of the most fundamental nuclear excitations and it dominates the dipole response of all nuclei. Its evolution from a single-humped structure to a double-humped one is considered as one of the prime signatures of nuclear deformation. Yet, its $\gamma$-decay behavior, despite being a key property, is still poorly characterized.

Recently, novel data on the γ-decay of the GDR of the well-deformed nuclide $^{154}$Sm and the spherical $^{140}$Ce were obtained through photonuclear experiments at the HI$\gamma$S facility. Individual regions of the GDR were selectively excited by intense, linearly-polarized and quasi-monochromatic $\gamma$-ray beams provided by HI$\gamma$S. This enabled an excitation-energy resolved determination of the GDR's $\gamma$-decay behavior. For $^{154}$Sm, in particular, the newly obtained data allow for a first experimental test of the commonly accepted K-quantum-number assignments to the double-humped GDR observed in deformed nuclei. First results of the analysis will be presented and discussed with respect to the textbook interpretation of the GDR in deformed nuclei.

This research is supported in part by the State of Hesse through the LOEWE research grant Nuclear Photonics and the cluster project ELEMENTS and by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under grant numbers DE-FG02-97ER41041 and DE-FG02-97ER41033.

Speaker: Jörn Kleemann (TU Darmstadt)

Nuclear Photonics 2023 Presentation.pptx

10:25 AM → 10:45 AM Break

10:45 AM → 11:45 AM What's Next

Convener: Christopher Barty (University of California - Irvine)

10:45 AM Multi-Petawatt Physics Prioritization (MP3)

The Multi-Petawatt Physics Prioritization (MP3) Workshop [1] was a community-initiated workshop held at Sorbonne Université, Paris, France in April 2022. The MP3 workshop goal was to develop science questions that will guide research and future experiments using the new generation of multi-petawatt power laser systems. Multi-petawatt laser-plasma interactions enable unique high-energy particle and radiation sources that will facilitate new ways to address the range of science questions. The workshop identified three themes for the science questions, 1) Highest-energy phenomena in the universe, 2) The origin and nature of space-time and matter in the universe, and 3) Nuclear astrophysics and the age/course of the universe.

This talk will give an overview of the MP3 workshop report [1], and then particularly discuss the third science theme that considers how intense laser pulses, and the generated intense beams of energetic protons, neutrons and/or photons, can induce nuclear reactions, probe nuclear physics, and enable practical applications. The MP3 report examines two nuclear themed science questions:
• What can be learned about heavy-element formation using laser-driven nucleosynthesis in plasma conditions far-from-equilibrium?
• How can high-flux gamma sources generated from multi-PW lasers be used to explore hadronic physics (low-energy QCD)?

Laser-plasma enabled nuclear physics experiments may open new opportunities for the Nuclear Photonics community.

This study is based on work supported by the National Science Foundation under Award Number 2112770.

[1] A. Di Piazza, L. Willingale, J. D. Zuegel, “Multi-Petawatt Physics Prioritization (MP3)
Workshop report,” arXiv:2211.13187 (2022).

Speaker: Louise Willingale (University of Michigan)

Willingale_Nuclear_Photonics_2023.pdf

11:15 AM EP-OPAL – planning for a next-generation laser user facility dedicated to the study of ultra-high intensity laser-matter interactions

The University of Rochester’s Laboratory for Laser Energetics (UR/LLE) has proposed to the National Science Foundation (NSF) to design OMEGA EP-coupled Optical Parametric Amplifier Lines (EP OPAL), a user facility dedicated to the study of ultrahigh-intensity laser–matter interactions. A potential future implementation of EP OPAL would enable high-impact science with broad community interest in fields that include relativistic plasma physics, ultrahigh field science, high-energy particle beams, x- and gamma-ray sources, matter under extreme conditions, and nuclear physics.

Ultrahigh-peak-power lasers employ chirped-pulse amplification, a technique invented at UR/LLE and recognized by the 2018 Nobel Prize in Physics. UR/LLE proposed leveraging its current infrastructure to deliver two 25-PW laser beamlines with focused intensities up to 10$^{24}$ W/cm$^2$ along with four OMEGA EP kilojoule beamlines. The proposed OMEGA EP-coupled optical parametric amplifier lines (EP-OPAL) user facility will have kJ-class beamlines with nanosecond, picosecond, and femtosecond pulses to provide flexible experimental configurations in multiple target areas. This infrastructure would dramatically expand scientific opportunities, and leverage proven expertise in laser engineering, target diagnostics, and user-facility operations. A prototype Multi-Terawatt OPAL system completed in 2020 demonstrated scalable laser technology and provides a smaller user facility.

The proposed NSF Mid-scale Research Infrastructure (Mid-scale RI-1) design project will: (1) design the EP-OPAL facility, including OMEGA EP long-pulse beam transport to the two EP-OPAL target areas; (2) design and prototype actively cooled, high-energy laser amplifiers with shot cycle times of a few minutes that will increase experimental productivity by >10x over existing high-energy laser systems; (3) design and prototype large-optics production and characterization systems; and (4) design experimental systems and diagnostics to address a wide array of compelling science.

A future EP-OPAL facility will provide a unique laboratory platform for exploring four areas of frontier research. Particle Acceleration and Advanced Light Sources (PAALS) promises accelerating electrons and ions beyond 100 GeV and 1 GeV energies, respectively. High-Field Physics and Quantum Electro-Dynamics (HFP/QED) will experimentally access particle and quantum radiation dynamics in the high-acceleration regime to test strong-field QED theories. Laboratory Astrophysics and Planetary Physics (LAPP) will build a bridge between the laboratory and astrophysical observations. Laser-Driven Nuclear Physics (LDNP) will employ proven and new regimes of ion acceleration and photon generation to provide a unique platform for testing modern nuclear theory, studying nuclear structure and nucleosynthesis, and offer novel methods of radiography and nuclear spectroscopy.

This material is based upon work supported by the U. S. Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856, the University of Rochester, and the New York State Energy Research and Development Authority.

Speaker: Jon Zuegel (Univ. of Rochester)

2023-09-15 Nuclear Photonics invited talk (Zuegel-FINAL).pdf

11:45 AM → 12:00 PM Announcements: Conference Closeout and Adjourn

Convener: Calvin Howell (Duke University and TUNL)

12:00 PM → 1:20 PM Lunch