Scattering cross sections of liquid deuterium for ultracold neutrons: Experimental results and a calculation model

TL;DR

This paper reports experimental measurements of ultracold neutron scattering cross sections in liquid deuterium at 20.6 K and introduces a calculation model that accurately fits the data, enhancing understanding of neutron interactions in liquid deuterium.

Contribution

It provides the first detailed experimental data and a validated calculation model for UCN scattering in liquid deuterium at cryogenic temperatures.

Findings

Measured scattering cross sections at 20.6 K.

The calculation model fits the experimental data well.

Incoherent approximation is acceptable for UCN in liquid deuterium.

Abstract

We present scattering cross sections $\sigma_\text{scatt}$ of ultracold neutrons (UCN) in liquid deuterium at T = 20.6 K, as recently measured by means of a transmission experiment. The indispensable thorough raw data treatment procedure is explained. A calculation model for coherent and incoherent scattering in liquid deuterium in the hydrodynamic limit based on appropriate physical concepts is provided and shown to fit the data well. The applicability of the incoherent approximation for UCN scattering in liquid deuterium was tested and found to deliver acceptable results.