Publications

Sep, 2026

Conference Paper

From Commissioning to Precision Data-Taking: Resolving Operational Challenges in the Nab Detector Systems

Our understanding of the weak mixing of quarks, described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix, currently presents an anomaly. Thanks to major strides in both theory and experiment, improved precision in determinations of the first row of matrix elements has revealed disagreement with the expectation of unitarity. The Nab experiment at the Spallation Neutron Sourc…

Aug, 2026

ORNL Report

A Real-time Solution for Fast-neutron Spectroscopy NA-22 Quarterly Report FY 26 Q3

Aug, 2026

Journal

Characterization of Low-energy Ionization Signals in Silicon Detectors for the Nab Experiment

The Nab (Neutron a b) experiment is designed to measure the beta-antineutrino angular correlation in free neutron 𝛽 decay with an ultimate precision goal of 0.1%, providing input for tests of Cabibbo-Kobayashi-Maskawa matrix unitarity. This measurement is performed via detection of electrons and protons in delayed coincidence using custom large-area segmented silicon detec…

May, 2026

Journal

Associated particle imaging of neutron inelastic scatter: 3-D reconstruction, capabilities, and challenges

Associated particle imaging (API) offers unique advantages for 3-D imaging of neutron inelastic scatter, including single-view tomographic imaging and data acquisition when access is limited to only one side of the interrogated object. However, widespread adoption of neutron inelastic scatter imaging has been impeded by several inherent challenges, most prominently spatial…

May, 2026

ORNL Report

A Real-time Solution for Fast-neutron Spectroscopy NA-22 Quarterly Report FY 26 Q2

Mar, 2026

Conference Paper

Improved field assessments of chemicals and explosives using high-resolution gamma-ray spectroscopy with a tagged neutron interrogation system

A field-portable tagged neutron interrogation system is being developed for detection of explosives and chemical warfare agents by prompt γ-ray neutron activation analysis. The system combines an associated particle imaging deuterium-tritium neutron generator with a high-purity germanium γ-ray detector. Fine spatial resolution neutron and α detectors enable precise mapping…

Mar, 2026

Journal

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 det…

Mar, 2026

ORNL Report

A Real-time Solution for Fast-neutron Spectroscopy NA-22 Quarterly Report FY 26 Q1

Oct, 2025

ORNL Report

Neutron Spectrometer Project NA-22 Quarterly Report (FY25Q4)

Jul, 2025

Journal

A Flexible Data Acquisition System Architecture for the Nab Experiment

Oct, 2024

Conference Paper

Study of neutron beta decay with the Nab experiment

The current three sigma tension in the unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix is a notable problem with the Standard Model of elementary particle physics. A long-standing goal of the study of free neutron beta decay is to better determine the CKM element Vud through measurements of the neutron lifetime and a decay correlation parameter. The Nab collab…

Aug, 2024

Journal

Delta-Rice: A HDF5 Compression Plugin optimized for Digitized Detector Data

An efficient method for high performance lossless compression of digitized analog signals within the HDF5 library and data format is presented. This algorithm was developed for the Nab experiment, a fundamental neutron physics experiment, but is broadly applicable to other experimental efforts requiring lossless compression of noisy data. This is a two-step process where c…