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Colloquium | Physics

Neutron Decay: Beta-Neutrino Correlation and Lifetime Experiments at NIST

PHY Colloquium

Abstract: Neutron beta decay provides a way to test the Standard Model without the complicating effects of nuclear structure. I will discuss the status of two neutron decay experiments on the fundamental physics beamline at NIST. The first experiment, called aCORN (“a” CORellation in Neutron decay), measures the beta-neutrino correlation commonly parameterized by the little a” coefficient. This experiment uses geometry and kinematics to turn the beta-neutrino angular distribution into a counting asymmetry. aCORN is in the last stages of analysis. I will also touch on a second experiment, with the imaginative name of BL3 (Beam Lifetime 3), which will measure the neutron lifetime. There is a discrepancy between two techniques for measuring the lifetime. This proposed experiment will explore the systematic errors in the beam technique to help resolve this discrepancy.