From Commissioning to Precision Data-Taking: Resolving Operational Challenges in the Nab Detector Systems
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 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 . 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.
Cite
@article{arxiv.2511.16678,
title = {From Commissioning to Precision Data-Taking: Resolving Operational Challenges in the Nab Detector Systems},
author = {L. J. Broussard and H. Acharya and R. Alarcon and S. Baeßler and M. Benoit and K. Borah and C. L. Britton and E. Brown and J. Choi and S. Clymer and C. Crawford and N. Ericson and L. Fabris and N. Fomin and J. Fry and R. Godri and F. M. Gonzalez and A. Hagemeier and J. Hamblen and S. Hollander and A. Jezghani and K. Leung and N. Macsai and M. Makela and D. Mathews and P. L. McGaughey and A. Mendelsohn and J. Mirabal and P. E. Mueller and A. Nelsen and S. I. Penttilä and D. Počanić and J. C. Ramsey and K. Reed and L. Richburg and A. Saunders and W. Schreyer and A. Shelby and A. R. Young},
journal= {arXiv preprint arXiv:2511.16678},
year = {2025}
}
Comments
Submitted to Proceedings of the 29th International Nuclear Physics Conference (INPC 2025), Daejeon, South Korea, 25 - 30 May 2025. 6 pages. 4 figures