Publications

Showing 6 results for Author: Wolfgang S. Schreyer

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  • 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…

  • Sep, 2026

    Conference Paper

    Neutron beta decay measurements with polarized neutrons and the Nab spectrometer

    A polarized neutron beam and the Nab spectrometer (pNAB) at the Spallation Neutron Source will enable simultaneous measurements of the beta (A) and neutrino (B) asymmetries in free neutron decay. Combined Nab and pNAB measurements of the correlation parameters a, A, and B will determine the axial-vector to vector coupling ratio in the weak interaction with a precision of a…

  • 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…

  • Feb, 2026

    ORNL Report

    Fundamental Nuclear and Particle Physics At Neutron Sources

    Fundamental neutron and neutrino physics at neutron sources, combining precision measurements and theory, probes new physics at energy scales well beyond the highest energies probed by the LHC and possible future high energy collider facilities. The European Spallation Source (ESS) will in the not too far future be the world’s most powerful pulsed neutron source and simult…

  • Jul, 2025

    Journal

    The pNab experiment and the quest for ever better neutron beam polarization

    The Nab and pNAB collaborations are conducting a program of studies of free neutron beta decay, with the primary goal of testing the unitarity of the Cabbibo-Kobayashi-Maskawa matrix that describes quark mixing due to the weak interaction. For this purpose, a large, novel electromagnetic spectrometer, the Nab spectrometer, has been designed, built, and placed in use to det…

  • 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…