arXiv subjects

Rebecca Godri

Publications and source records attributed to Rebecca Godri.

3 recordsLinked to original sources

arXiv2026

A gaseous-helium cooling system for silicon detectors in the Nab experiment

The Nab experiment aims to extract the neutron beta decay correlation coefficients 'a' and 'b'. This will be accomplished using a 7 m tall electromagnetic spectrometer which measures electron energies and proton momenta. Detection of electrons and protons resulting from neutron beta decay will be carried out using large-area, thick, highly-segmented, single-crystal silicon detectors. These detectors and accompanying electronics will be cooled by a recirculating, gaseous helium cooling system to below 150 K with +/- 0.5 K stability. We will motivate the need for detector cooling in the Nab experiment and discuss design and performance of this cooling system.

physics.ins-det↗

arXiv2025

First Full Dalitz Plot Measurement in Neutron $β$-Decay using the Nab Spectrometer and Implications for New Physics

Precision measurements of observables in neutron $β$-decay are used to test the Standard Model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source was constructed to measure correlations in neutron decay by utilizing an asymmetric spectrometer and novel detection system to accurately reconstruct the proton momentum and electron energy for each $β$-decay. This work describes the detection of neutron $β$-decay products in the Nab spectrometer and presents the first full Dalitz plot representation of the phase space of neutron $β$-decay for all electrons >100 keV. In addition, new constraints are placed on a possible excited neutron state, hypothesized to explain the disagreement between the appearance and disappearance neutron lifetime techniques.

nucl-ex↗

arXiv2024

A Method for Proton Detector Efficiency Measurement with Applications in Neutron Beta Decay and Lifetime Experiments

This article proposes a new method to measure the proton detector efficiency for use in "beam" determinations of the free neutron lifetime. There is currently a 4σ disagreement between the "beam" and "storage" methods of measuring the lifetime of the neutron. A possible reason for this is a systematic uncertainty that is not properly accounted for in one or both types of experiments. Absolute proton counting is an essential facet of the "beam" experimental approach. The absolute detector efficiency is not currently known for existing experiments and could be a source of a hidden systematic error. The proposed absolute calibration techniques can also be extended to new, large area particle detectors designed for future experiments. We propose to laser ionize a beam of atomic hydrogen and simultaneously count both the outgoing protons and electrons. Due to recent advances in UV laser and atomic hydrogen beam technologies, we estimate a count rate as high as ~200k proton-electrons pairs per second under the most favorable scheme discussed. Our proposed technique would remove one of the leading systematic uncertainties in the determination of the neutron lifetime, making an precision of {\pm}0.16 s feasible. Precise and accurate knowledge of the proton detection efficiency is crucial to fully understanding the systematics of the "beam" measurement method as well as developing next generation experiments that will have the precision to test the Standard Model.

physics.ins-det↗