UCN transport simulation in solid deuterium crystals

TL;DR

This paper presents a Monte Carlo simulation study of ultracold neutron transport in disordered solid deuterium crystals, focusing on how density fluctuations affect neutron transparency and extraction efficiency.

Contribution

It introduces a novel simulation approach using correlation functions derived from experimental cross section data to model neutron transport in disordered solid deuterium.

Findings

Neutron transparency is significantly affected by disorder in the crystal structure.

The simulation provides insights into optimizing moderator materials for better UCN extraction.

Density fluctuations play a crucial role in neutron transport properties.

Abstract

The extraction efficiency of ultracold neutrons from cryogenic moderators depends critically on the neutron transparency of the moderator material. The Monte Carlo simulation of the probability of the UCN going out from non-ideal (disordered) solid deuterium crystals has been performed. It was based on the use of the correlation function describing the density fluctuations in a disordered material, the latter being inferred from the measured very low neutron energy total cross sections for this material.