Prompt: Probability-conserved cross section biasing Monte Carlo particle transport system

Abstract

An open source software package for simulating thermal neutron propagation in geometry is presented. In this system, neutron propagation can be treated by either the particle transport method or the ray-tracing method. Supported by an accurate backend scattering physics engine, this system is capable of reproducing neutron scattering experiments in complex geometries and is expected to be used in the areas of instrument characterisation, optimisation and data analysis.In this paper, the relevant theories are briefly introduced. The simulation flow and the user input syntax to control it are provided in detail. Five benchmarking simulations, focusing on different aspects of simulation and scattering techniques, are given to demonstrate the applications of this simulation system. They include an idealised total scattering instrument, a monochromatic powder diffractometer, a neutron guide, a chopper and an imaging setup for complex geometries. Simulated results are benchmarked against experimental data or well-established software packages when appropriate. Good agreements are observed. Program summaryProgram Title:PromptCPC Library link to program files:https://doi.org/10.17632/337frmp9ky.1Developer's repository link:https://gitlab.com/cinema-developers/promptLicensing provisions:Apache-2.0Programming language:C++, C and PythonExternal routines/libraries:NCrystal, VecGeom, MCPL, PyVistaNature of problem: It is challenging for traditional neutron ray-tracing simulation methods to consider multiple scatterings in complex geometries, hence the accuracy and precision of the simulated neutron scattering experiments are limited.Solution method: A hybrid system of Monte Carlo particle transport method and ray-tracing method is proposed.