GAMMA-RAY TRANSPORT CALCULATION INCLUDING BREMSSTRAHLUNG BY MONTE-CARLO CODE MORSE

Bremsstrahlung photon estimation was added to gamma-ray transport calculation to improve the accuracy of neutron gamma-ray calculation. The validity of bremsstrahlung photon production calculation was examined numerically using a Monte Carlo code. Error due to neglect of electron multiple scattering was estimated, which showed the essential importance of effect of electron multiple scattering to estimation of bremsstrahlung photons in gamma-ray transport calculation. To calculate electron multiple scattering in a simple way with sufficient accuracy, electrons are assumed to reach complete diffusion state prior to its bremsstrahlung photon emission. Electron angular distribution at its bremsstrahlung photon emission is assumed to be Gaussian distribution. Calculation by this method is compared with the experimental data, and the result of exact calculation. The validity of this method was shown by the agreement in sufficient accuracy between them. A Monte Carlo code MORSE-CG was improved to do all the numerical calculation of this work. The new code is called as MORSE-BREM.