arXiv subjects

Josh Pierce

Publications and source records attributed to Josh Pierce.

3 recordsLinked to original sources

arXiv2026

Development and extension of a monochromatic neutron beamline for neutron polarimetry device characterization at the Spallation Neutron Source

The precise manipulation and analysis of neutron spin states are foundational for a wide range of physics experiments, from fundamental symmetry tests to materials science. To enable systematic characterization of neutron polarimetry devices, we have constructed and extended a monochromatic neutron beamline at the Spallation Neutron Source, Oak Ridge National Laboratory. The beamline delivers monochromatic neutrons and provides a flexible platform for deploying and evaluating advanced neutron spin manipulation instruments. We describe the design and commissioning of the extended beamline and present a proof-of-concept neutron polarimetry study using three devices: a supermirror neutron polarizer, a Mezei spin flipper, and an in situ neutron 3He spin analyzer system. Performance metrics, optimization strategies, and systematic effects are discussed, demonstrating the beamline utility for neutron instrumentation testing. These results establish the extended monochromatic beamline as a useful resource for the development and validation of neutron polarimetry technologies.

physics.ins-det↗

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 $\beta$-Decay using the Nab Spectrometer and Implications for New Physics

Precision measurements of observables in neutron $\beta$-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 $\beta$-decay. This work describes the detection of neutron $\beta$-decay products in the Nab spectrometer and presents the first full Dalitz plot representation of the phase space of neutron $\beta$-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↗