Speaker
Description
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
