Precision Measurements with Neutrons

This proposal describes experimental contributions to the development of a search for the Time-Reversal-Symmetry-violating (T-violating) neutron electric dipole moment (EDM) to be carried out at the Spallation Neutron Source (i.e., the nEDM Experiment at the SNS), and to a continued program on precision measurements of neutron beta decay observables employing the ultracold neutron (UCN) source in operation at the Los Alamos National Laboratory (i.e., the UCNA Experiment at LANL). The nEDM Experiment has recently entered a four-year ¡§Critical Component Demonstration¡¨ (CCD) phase, for which the goal is to demonstrate the main internal components of the experiment are at a sufficient level of readiness for large-scale integration. This proposal will support activity during the experiments CCD phase on the development of a magnetic field monitoring system, which is designed to provide complementary information to that obtained from the experiments 3He co-magnetometer. The concept of this field monitoring system, for which the intellectual idea was developed by the PI for this proposal, permits for reconstruction of the spatial dependence of the vector components of the magnetic field, and thus the magnetic field gradients, in the interior measurement volume solely from exterior measurements of the vector field components. Prototypes of the monitoring system will be developed, with the goal of demonstrating reconstruction of the interior field gradients to the desired level of accuracy. The UCNA Experiment is focused on a high-precision measurement of the Parity-Violating neutron beta-asymmetry parameter. This proposal will support the PI¡¦s long-standing physics contributions to the experiment, including especially the data analysis and the investigation of systematic uncertainties. An upgrade to the LANL UCN source is currently underway, with a new source insert and cold moderator scheduled to be installed prior to the start of the 2015 run cycle. The projected increased flux of UCN will permit high-statistics data taking runs in 2015 and 2016. This proposal will support data analysis efforts and the ultimate extraction of the physics result. Concurrently, ongoing synergistic phenomenological work carried out in collaboration with a theorist (Prof. S. Gardner, U. Kentucky) will assess the ability of upcoming fundamental symmetries experiments to probe new physics in the presence of theoretical uncertainties.