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

Authors

• L. J. Broussard, Oak Ridge National Laboratory
• H. Acharya, University of Kentucky
• R. Alarcon, Arizona State University
• S. Baeßler, Oak Ridge National Laboratory
• M. Benoit, Oak Ridge National Laboratory
• K. Borah, University of Kentucky
• C. L. Britton, Oak Ridge National Laboratory
• E. Brown, University of Tennessee, Knoxville
• J. Choi, North Carolina State University
• S. Clymer, Arizona State University
• C. Crawford, University of Kentucky
• N. Ericson, Oak Ridge National Laboratory
• L. Fabris, Oak Ridge National Laboratory
• N. Fomin, University of Tennessee, Knoxville
• J. Fry, Eastern Kentucky University
• R. Godri, University of Tennessee, Knoxville
• F. M. Gonzalez, Oak Ridge National Laboratory
• A. Hagemeier, University of Virginia
• J. Hamblen, University of Tennessee at Chattanooga
• S. Hollander, Oak Ridge National Laboratory
• A. Jezghani, Georgia Tech
• K. Leung, Montclair State UniversityFollow
• N. Macsai, University of Manitoba
• M. Makela, Los Alamos National Laboratory
• D. Mathews, Oak Ridge National Laboratory
• P. L. McGaughey, Los Alamos National Laboratory
• A. Mendelsohn, University of Manitoba
• J. Mirabal, Los Alamos National Laboratory
• P. E. Mueller, Oak Ridge National Laboratory
• A. Nelsen, University of Kentucky
• S. I. Penttilä, Oak Ridge National Laboratory
• D. Počanić, University of Virginia
• J. C. Ramsey, Oak Ridge National Laboratory
• K. Reed, Oak Ridge National Laboratory
• L. Richburg, University of Tennessee, Knoxville
• A. Saunders, Oak Ridge National Laboratory
• W. Schreyer, Oak Ridge National Laboratory
• A. Shelby, North Carolina State University
• A. R. Young, North Carolina State University

Document Type

Conference Proceeding

Publication Date

8-5-2026

Journal / Book Title

The 29th International Nuclear Physics Conference (INPC 2025)

Abstract

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 Source is designed to precisely extract the first matrix element Vud and shed light on experimental tensions within the neutron beta decay dataset. Nab’s asymmetric spectrometer allows coincident reconstruction of the decay proton and electron energies, which will be used to determine the electron-neutrino correlation coefficient, and thus (with the neutron lifetime) determine Vud. This unique approach has provided a more comprehensive view of neutron beta decay, including a first observation of the full momentum phase space of the decay above detector thresholds and limits on exotic neutron states. Recent upgrades to the Nab detector system have improved the robustness and stability of the detector performance in terms of proton detection efficiency, noise performance, and detector segment availability, setting the stage for high precision physics data-taking.

DOI

10.1051/epjconf/202637804001

MSU Digital Commons Citation

Broussard, L. J.; Acharya, H.; Alarcon, R.; Baeßler, S.; Benoit, M.; Borah, K.; Britton, C. L.; Brown, E.; Choi, J.; Clymer, S.; Crawford, C.; Ericson, N.; Fabris, L.; Fomin, N.; Fry, J.; Godri, R.; Gonzalez, F. M.; Hagemeier, A.; Hamblen, J.; Hollander, S.; Jezghani, A.; Leung, K.; Macsai, N.; Makela, M.; Mathews, D.; McGaughey, P. L.; Mendelsohn, A.; Mirabal, J.; Mueller, P. E.; Nelsen, A.; Penttilä, S. I.; Počanić, D.; Ramsey, J. C.; Reed, K.; Richburg, L.; Saunders, A.; Schreyer, W.; Shelby, A.; and Young, A. R., "From Commissioning to Precision Data-Taking: Resolving Operational Challenges in the Nab Detector Systems" (2026). Department of Physics and Astronomy Faculty Scholarship and Creative Works. 170.
https://digitalcommons.montclair.edu/physics-astron-facpubs/170

Rights

This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0.

Published Citation

Broussard, L. J., et al. “From Commissioning to Precision Data-Taking: Resolving Operational Challenges in the Nab Detector Systems.” EPJ Web of Conferences, vol. 378, 2026, p. 04001., https://doi.org/10.1051/epjconf/202637804001.