In-situ measurement of the velocity spectrum of ultracold neutrons and its evolution using an oscillating detector

TL;DR

This paper introduces a novel in-situ method using an oscillating detector to measure and monitor the velocity spectrum of ultracold neutrons, crucial for precision experiments in fundamental physics.

Contribution

It presents a new in-situ UCN spectrometer that measures the velocity distribution and its evolution, aiding in systematic effects analysis and spectrum monitoring.

Findings

Successful in-situ measurement of UCN velocity spectrum

Demonstrated spectrum monitoring during UCN transport

Potential for improved systematic effects control

Abstract

Ultracold neutrons (UCNs) are used in experiments investigating fundamental interactions, testing the Standard Model of particle physics and searching for phenomena beyond it. Knowledge of the energy spectrum of UCNs is very often a key ingredient to determine the systematic effects in precision measurements utilizing UCNs. The proposed novel method allows for the in-situ measurements of the UCN velocity distribution and its time evolution. In addition, the proposed UCN spectrometer can be a handy diagnostic tool for monitoring the spectrum in critical places in the UCN transport system connecting an UCN source with experiments. In this paper, we show the results from the measurements performed at the Paul Scherrer Institute's UCN source.