Measurement of Neutron Decay Parameters—The abBA Experiment |
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| Authors: | W S Wilburn J D Bowman G S Mitchell J M O’Donnell S I Penttila P-N Seo J R Calarco F W Hersmann T E Chupp T V Cianciolo K P Rykaczewski G R Young R T De Souza W M Snow D Desai G L Greene R K Grzywacz E Frlez D Pocanic T R Gentile V Gudkov G L Jones |
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| Affiliation: | Los Alamos National Laboratory, Los Alamos, NM 87544;University of New Hampshire, Durham, NH 03824;University of Michigan, Ann Arbor, MI 48109;Oak Ridge National Laboratory, Oak Ridge, TN 37831;Indiana University, Bloomington, IN 47408;University of Tennessee, Knoxville, TN 37996;University of Virginia, Charlottesville, VA 22904;National Institute of Standards and Technology, Gaithersburg, MD 20899;University of South Carolina, Columbia, SC 29208;Hamilton College, Clinton, NY 13323 |
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| Abstract: | We are developing an experiment to measure the correlations a, A, and B, and the Fierz interference term b in neutron decay, with a precision of approximately 10−4. The experiment uses an electromagnetic spectrometer in combination with two large-area segmented silicon detectors to detect the proton and electron from the decay in coincidence, with 4π acceptance for both particles. For the neutron-polarization-dependent observables A and B, precision neutron polarimetry is achieved through the combination of a pulsed neutron beam, under construction at the SNS, and a polarized 3He neutron polarizer. Measuring a and A in the same apparatus provides a redundant determination of λ = gA/gV. Uncertainty in λ dominates the uncertainty of CKM unitarity tests. |
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| Keywords: | neutron beta decay weak interactions |
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