Understanding Ultracold Neutron Production in Oxygen Solids from Volume and Temperature Dependent Yields

TL;DR

This study investigates ultracold neutron production in solid oxygen across temperatures from 5 K to 50 K, using experiments and simulations to understand scattering processes and validate cross-sections.

Contribution

It provides experimental data and a combined analysis validating UCN production models and highlighting magnetic scattering effects in solid oxygen.

Findings

Validated UCN production and upscattering cross-sections.

Identified role of magnetic scattering in UCN enhancement.

Demonstrated temperature dependence of UCN yields.

Abstract

We present experimental data on ultracold neutron (UCN) production in solid oxygen from 5 K to 50 K. The experiment used 3 cells of different dimensions in order to study the excess UCN elastic scattering in s-O$_2$ due to source density non-uniformities. We present a combined $\chi^2$ analysis with the aid of Monte-Carlo simulations which contain the detailed physics of UCN transport as well as cold neutron attenuation. The results validate the UCN production and upscattering cross-sections extracted from the dynamic structure function derived from inelastic neutron scattering, and illustrate the role of magnetic scattering in enhancing UCN production in s-O$_2$.