Benjamin Barber

Document Type

Poster Presentation

Celebration Date



Physicists from Argonne National Laboratories, Valparaiso University, the University of Hawaii, and the National Institute for Standards and Technology have designed an experiment to use the known neutron magnetic dipole moment (nMDM) to measure Schwinger scattering in silicon (Si), a process whereby the orientation of the magnetic dipole polarization is altered by interactions with the atomic electric fields in a Si crystal. This measurement is intended to be a precursor to a search for a neutron electric dipole moment (nEDM) employing a similar spin rotation via a different interaction. Both measurements depend on neutron Bragg reflections down a slotted Si crystal. For a successful measurement, the neutron beam has to reflect approximately 150 times, without a large loss of beam intensity. This requires a high reflectivity, on the order of 99% reflective. In order to make an accurate measurement of the Schwinger scattering, both the incident neutron beam and the crystal's reflectivity need to be well understood. In summer 2010, we characterized the newly commissioned 'nMDM Experiment' neutron beamline at the NIST Center for Neutron Research, and measured the reflectivity of the slotted Si single crystal intended for the experiment. These measurements laid the groundwork for the coming nMDM Schwinger scattering measurement.

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