Temperature Dependence of the UCN Loss Rate

TL;DR

This study investigates how ultra cold neutron loss rates vary with temperature at low temperatures down to 4K, providing insights into neutron-surface interactions and supporting the 1/v loss model over the subbarrier model.

Contribution

First experimental results on UCN loss rates at low temperatures using a new cryostat, supporting the 1/v model and explaining low temperature upscattering.

Findings

Ruled out the subbarrier model for UCN loss.

Supported the 1/v loss model at low temperatures.

Proposed an explanation for low temperature upscattering.

Abstract

We report about the first results obtained with our Ultra High Vacuum cryostat recently commissioned at HMI to study Ultra Cold Neutrons(UCN) loss rate under low temperatures(down to 4K) and well controlled sample environment. Our analysis of the temperature dependence of UCN loss rate on Cu surface allowed us to rule out the subbarier model in support of the 1/v model and propose a reasonable explanation of the low temperature upscattering.