High Precision Measurements of Beta Decay Using Neutron Beams and Ultracold Neutrons

Albert R. Young
Paul R. Huffman
Daniel D Stancil

Project runs from 08/01/2022 to 07/31/2025
$355,521

This renewal award seeks funding to begin the operation of the Nab experiment at the SNS and to continue work on the UCNtau experiment at LANL, including playing a role in an upgrade activity currently underway. Our effort is motivated by the impact to nuclear physics, particle physics and cosmology, where the proposed measurements will establish the parameters of the charged weak current using neutron data, which does not suffer from nuclear structure-related uncertainties. The Nab experiment at the SNS will determine the correlation between the emitted electron and anti-neutrino through a measurement of the time-of-flight through a magnetic spectrometer optimized to measure proton velocities. The precision-level we target is 0.12%. The UCNtau experiment is already the most precise lifetime experiment, but we seek roughly another factor of three improvement in the sensitivity, based on an upgrade to a geometry referred to as “UCNtau+”. Our work will involve participation in the operation of these experiments, as well as simulation and analysis of the results.