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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