Project Details
The first two experiments at the Spallation Neutron Source (SNS) Fundamental Neutron Physics Beamline (FNPB) measured parity-violating (PV) asymmetries in neutron capture in light nuclear systems in order to elucidate the weak interaction in hadronic systems. The NPDGamma experiment measured the difference in gamma-ray yield parallel and anti-parallel to the neutron spin following capture of a polarized neutron beam on a liquid hydrogen target. The n3He experiment measured the difference in proton yield parallel and anti-parallel to the neutron spin following capture of a polarized neutron beam on a 3He-filled active target. The experimental apparatus (mostly common between the two experiments) is shown in the figure. Data collection is complete; both experiments achieved uncertainties near or below the part-per-billion level. Final publications are in preparation and/or submitted.
Additional information on the fundamental neutron physics beamline can be found here: https://neutrons.ornl.gov/fnpb
Contact: Seppo Penttila (penttilasi@ornl.gov)
