Development of a reaction ejectile sampling algorithm to recover kinematic correlations from inclusive cross-section data in Monte-Carlo particle transport simulations

Ogawa, Tatsuhiko   ; Sato, Tatsuhiko   ; Hashimoto, Shintaro  ; Niita, Koji*

A new theoretical approach is developed to reproduce the stochastic distributions of secondary particle energy and angle with conservation of momentum and energy in reactions ejecting more than one ejectiles using inclusive cross-section data. The summation of energy and momentum in each reaction is generally not conserved in Monte-Carlo particle transport simulation based on the inclusive cross-sections because the particle correlations are lost in the inclusive cross-section data. However, the energy and angular distributions are successfully reproduced by randomly generating numerous sets of reaction-final-state configurations which are compliant with the conservation laws, and sampling one set considering their likelihood. This developed approach was applied to simulation of (n,xn) reactions (x 2) of various targets and to other reactions such as (n,np) and (n,2n). The calculated secondary particle energy and angular distributions were compared with those of the original inclusive cross-section data to validate the algorithm. The calculated distributions reproduce the trend of original cross-section data considerably well, and the agreement between the calculated and the original data is particularly good for heavy targets. This approach is beneficial to improve the accuracy of event-by-event analysis in particle transport simulation, which is critical for soft-error analyses and detector performance prediction.