Radiological Protection Study of a Radioisotope Production Scenario of a Laser-based Proton Accelerator

摘要

One of the most attractive applications of laser-based particle accelerators is the on-site generation of radioisotopes. Laser-accelerated protons can be used as projectiles to induce nuclear reactions in a suitable target material. Our group has studied in detail the different sources of risk existing in a realistic production scenario. The first step addresses the laser-target interaction that involves the proton generation and the accompanying multi-MeV electrons. In the second one, the laser-accelerated protons are guided to the secondary target to induce the specific nuclear reaction. An analytic-quantitative estimation of equivalent dose has been calculated. We have selected a set of broad electron energy spectra following a Boltzmann distribution for energies from 0.5 MeV to 20 MeV. The total number of electrons is 10~(11) per shot. The scenario of radioisotope production requires 30 minutes of irradiation at 100 Hz repetition rate. In addition, a Montecarlo simulation has been performed simulating the same scenario in order to obtain a 3D dosimetric map of the surrounding areas. The deposited dose due to the activity of the radioisotope has been calculated analytically for the nuclear reaction ~(11)B(p,n)~(11)C assuming a linear activity increase to 0.5 GBq during the irradiation time. This process will generate a total number of neutrons around 5·10~9. A Montecarlo simulation to estimate their dosimetric impact has been performed as well.