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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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....
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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]...
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...
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...
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,...
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...
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...
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...
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,...
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,...
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....
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....
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...
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...
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...
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...
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...
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....
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...
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...
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...
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...
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...
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...
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...
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...
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....
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...
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 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...
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...
The application of laser plasma accelerated proton beams [1] in radiation therapy of cancer has been discussed almost since the first demonstration of plasma accelerators reaching 10’s of MeV energies. It was initially motivated by accelerator compactness and cost efficiency, promising a wider spread of advanced therapy methods. Thus, the radiobiology of these intense particle bunches was...
