Monte Carlo code for the damage of bio-molecules irradiated by X-ray free electron lasers; Incorporation of election impact ionization processes

Moribayashi, Kengo

This paper develops a Monte Carlo (MC) code for the calculation of the damage and the movement of free and quasi-free electrons, which are produced from the irradiation of X-ray free electron laser (XFEL) light pulses. Ionization processes such as X-ray absorption, Compton scattering, and Auger are treated by MC. On the other hand, the movements of free and quasi- free electrons are controlled by the Newton equations. Electron impact ionization processes occur when quasi-free electrons pass through the cross sections, which is assigned to atoms and ions. In order to confirm the accuracy of the calculations using our MC code, we compare the frequency of photo-electron impact ionization processes calculated by our MC code with that by the rate equations for spherical targets. Then, we have found agreement of 80 % to 90 % for the values of the frequency.