Optimization design for energy response of the mobile radioactive gas monitor

[Background] The mobile radioactive gas monitor responses differently to gamma rays at different energies. [Purpose] This study aims to accurately measure the dose of gamma radiation monitor by means of compensation for energy response. [Methods] Energy responses of NaI(Tl) crystals in the monitor in different lead-hole models were simulated using Monte Carlo N Particle Transport Code (MCNP) software. Various sizes of shielding lead hole were selected to compare the standard deviations of different models, and the optimum size of shielding lead hole was obtained. [Results and Conclusion] The simulation result shows that the energy response of monitor is best compensated when the radius of hole is 3.0 cm and thickness of shielding lead is 0.5 cm. (authors)