Detection System for Neutron $\beta$ Decay Correlations in the UCNB and Nab experiments

TL;DR

This paper presents a highly segmented silicon detection system designed for precise measurement of neutron beta decay correlations, demonstrating successful detection of decay particles and readiness for implementation in key experiments.

Contribution

The paper introduces a novel silicon detector system with specific performance metrics, tailored for neutron beta decay correlation measurements in UCNB and Nab experiments.

Findings

Achieved energy thresholds below 10 keV for beta electrons.

Demonstrated coincident detection of beta particles and recoil protons.

System meets specifications for energy resolution and timing.

Abstract

We describe a detection system designed for precise measurements of angular correlations in neutron $\beta$ decay. The system is based on thick, large area, highly segmented silicon detectors developed in collaboration with Micron Semiconductor, Ltd. The prototype system meets specifications for $\beta$ electron detection with energy thresholds below 10 keV, energy resolution of $\sim$3 keV FWHM, and rise time of $\sim$50 ns with 19 of the 127 detector pixels instrumented. Using ultracold neutrons at the Los Alamos Neutron Science Center, we have demonstrated the coincident detection of $\beta$ particles and recoil protons from neutron $\beta$ decay. The fully instrumented detection system will be implemented in the UCNB and Nab experiments, to determine the neutron $\beta$ decay parameters $B$, $a$, and $b$.