MCViNE -- An object oriented Monte Carlo neutron ray tracing simulation package

TL;DR

MCViNE is a flexible, object-oriented Monte Carlo neutron ray tracing software that enables detailed simulations of neutron scattering experiments, aiding in understanding complex scattering mechanisms and instrument design.

Contribution

It introduces modern software engineering practices into neutron ray tracing, allowing for sophisticated, customizable simulations of neutron scattering with complex samples and environments.

Findings

Successfully simulated neutron scattering experiments matching experimental results.

Enabled detailed analysis of scattering mechanisms like phonon and magnon interactions.

Demonstrated flexibility in handling complex detector systems and multiple scattering events.

Abstract

MCViNE (Monte-Carlo VIrtual Neutron Experiment) is a versatile Monte Carlo (MC) neutron ray-tracing program that provides researchers with tools for performing computer modeling and simulations that mirror real neutron scattering experiments. By adopting modern software engineering practices such as using composite and visitor design patterns for representing and accessing neutron scatterers, and using recursive algorithms for multiple scattering, MCViNE is flexible enough to handle sophisticated neutron scattering problems including, for example, neutron detection by complex detector systems, and single and multiple scattering events in a variety of samples and sample environments. In addition, MCViNE can take advantage of simulation components in linear-chain-based MC ray tracing packages widely used in instrument design and optimization, as well as NumPy-based components that make prototypes useful and easy to develop. These developments have enabled us to carry out detailed simulations of neutron scattering experiments with non-trivial samples in time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. With simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.