Geant4 Monte Carlo simulation study of the secondary radiation fields at the laser-driven ion source LION

Abstract

At the Center for Advanced Laser Applications (CALA), Garching, Germany, the LION (Laser-driven ION Acceleration) experiment is being commissioned, aiming at the production of laser-driven bunches of protons and light ions with multi-MeV energies and repetition frequency up to 1 Hz. A Geant4 Monte Carlo-based study of the secondary neutron and photon fields expected during LION’s different commissioning phases is presented. Goal of this study is the characterization of the secondary radiation environment present inside and outside the LION cave. Three different primary proton spectra, taken from experimental results reported in the literature and representative of three different future stages of the LION’s commissioning path are used. Together with protons, also electrons are emitted through laser-target interaction and are also responsible for the production of secondary radiation. For the electron component of the three source terms, a simplified exponential model is used. Moreover, in order to reduce the simulation complexity, a two-components simplified geometrical model of proton and electron sources is proposed. It has been found that the radiation environment inside the experimental cave is either dominated by photons or neutrons depending on the position in the room and the source term used. The higher the intensity of the source, the higher the neutron contribution to the total dose for all scored positions. Maximum neutron and photon ambient dose equivalent values normalized to 109 simulated incident primaries were calculated at the exit of the vacuum chamber, where values of about 85 nSv (109 primaries)−1 and 1.0 μSv (109 primaries)−1 were found.

Analisa Distribusi Dosis Pada Fantom Homogen Dan Inhomogen Dengan Simulasi Monte Carlo

“…Dosis yang yang diakibatkan oleh energi deposisi tersebut menghasilkan data distribusi dosis 3 dimensi. Saat ini, beberapa kode MC yang digunakan dalam aplikasi radioterapi banyak dikembangkan, yakni electron gamma shower (EGSnrc) [4], MCNP [5], Geant4 [6], FLUKA [7], dan PHITS [8]. Hasil simulasi kode-kode MC ini menghasilkan data distribusi dosis.…”