分类: 物理学 >> 核物理学 提交时间: 2023-05-23
摘要: In this study, we theoretically investigate the feasibility of using laser-wakefield accelerated (LWFA) electrons for the photonuclear measurement of nuclear isomers according to the characteristics of the electrons obtained from LWFA experiments conducted at the Compact Laser Plasma Accelerator (CLAPA) laboratory. The experiments at the CLAPA show that a stable electron beam with an energy of 78135 MeV and a charge of 300-600 pC can be obtained. The bremsstrahlung spectra were simulated using Geant4, which suggests that a bremsstrahlung source with a peak intensity of 1019 photons/s can be generated. Theoretical calculations of isomer production cross-sections from the photonuclear reactions on six target nuclei, 197Au, 180Hf, 159Tb, 115In, 103Rh, and 90Zr were performed and compared with the available experimental data in EXFOR, which suggest that further experiments are required for a series of photonuclear reaction channels. Flux-averaged cross-sections and isomer ratios (IR) resulting from such bremsstrahlung sources are theoretically deduced. The results suggest that IR measurements can be used to constrain nuclear components, such as strength function and optical model potential. In addition, the detection of the decay characteristics was evaluated with Geant4 simulations. The use of the LWFA electron beam and its bremsstrahlung for photonuclear studies involving nuclear isomers is anticipated.
分类: 物理学 >> 核物理学 提交时间: 2023-10-17
摘要: The simultaneous measurement of the spatial profile and spectrum of laser-accelerated protons is important for further optimization of the beam qualities and applications. We report a detailed study regarding the underlying physics and regular procedure of such a measurement through the radioactivation of a stack composed of aluminum, copper, and CR-39 plates as well as radiochromic films (RCFs). After being radioactivated, the copper plates are placed on imaging plates (IPs) to detect the positrons emitted by the reaction products through contact imaging. The spectrum and energy-dependent spatial profile of the protons are then obtained from the IPs and confirmed by the measured ones from the RCFs and CR-39 plates. We also discuss the detection range, influence of electrons, radiation safety, and spatial resolution of this measurement. Finally, insights regarding the extension of the current method to online measurements and dynamic proton imaging are also provided.