Human radiological safety assessment for petawatt laser-driven ion acceleration experiments in CLAPA-T

The newly built Compact Laser Plasma Accelerator–Therapy facility at Peking University will deliver 60 J/1 Hz laser pulses with 30 fs duration. Driven by this petawatt laser facility, proton beams with energy up to 200 MeV are expected to be generated for tumor therapy. During high-repetition operation, both prompt radiation and residual radiation may cause safety problems. Therefore, human radiological safety assessment before commissioning is essential. In this paper, we simulate both prompt and residual radiation using the Geant4 and FLUKA Monte Carlo codes with reasonable proton and as-produced electron beam parameters. We find that the prompt radiation can be shielded well by the concrete wall of the experimental hall, but the risk from residual radiation is nonnegligible and necessitates adequate radiation cooling. On the basis of the simulation results, we discuss the constraints imposed by radiation safety considerations on the annual working time, and we propose radiation cooling strategies for different shooting modes.