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Improved limits on Fierz interference using asymmetry measurements from the Ultracold Neutron Asymmetry (UCNA) experiment

Sun, X. and Blatnik, M. and Carr, R. and Filippone, B. W. and Hickerson, K. P. and Martin, J. W. and Mendenhall, M. P. and Pérez Galván, A. and Picker, R. and Slutsky, S. and Swank, C. and Wei, W. (2020) Improved limits on Fierz interference using asymmetry measurements from the Ultracold Neutron Asymmetry (UCNA) experiment. Physical Review C, 101 (3). Art. No. 035503. ISSN 2469-9985.

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The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the β-decay asymmetry parameter, A₀, for free neutron decay. In the experiment, polarized ultracold neutrons are transported into a decay trap, and their β-decay electrons are detected with ≈4π acceptance into two detector packages which provide position and energy reconstruction. The experiment also has sensitivity to b_n, the Fierz interference term in the neutron β-decay rate. In this work, we determine b_n from the energy dependence of A₀ using the data taken during the UCNA 2011-2013 run. In addition, we present the same type of analysis using the earlier 2010 A dataset. Motivated by improved statistics and comparable systematic errors compared to the 2010 data-taking run, we present a new b_n measurement using the weighted average of our asymmetry dataset fits, to obtain b_n = 0.066±0.041_(stat)±0.024_(syst) which corresponds to a limit of −0.012 < b_n < 0.144 at the 90% confidence level.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Sun, X.0000-0001-8817-4643
Filippone, B. W.0000-0002-2618-2688
Hickerson, K. P.0000-0001-7647-119X
Wei, W.0000-0002-9670-4787
Alternate Title:Improved limits on Fierz Interference using asymmetry measurements from the UCNA experiment
Additional Information:© 2020 American Physical Society. Received 17 November 2019; Accepted 25 February 2020; Published 16 March 2020. This work is supported in part by the U.S. Department of Energy, Office of Nuclear Physics (DE-FG02-08ER41557, DE-SC0014622, DE-FG02-97ER41042) and the National Science Foundation (1002814, 1005233, 1205977, 1306997, 1307426, 1506459, 1615153, 1812340, and 1914133). Furthermore, we gratefully acknowledge the support of the LDRD program (20110043DR), and the help of those at the Accelerator Operations and Technology division at Los Alamos National Laboratory.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-08ER41557
Department of Energy (DOE)DE-SC0014622
Department of Energy (DOE)DE-FG02-97ER41042
Los Alamos National Laboratory20110043DR
Issue or Number:3
Record Number:CaltechAUTHORS:20191203-074001740
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100156
Deposited By: Tony Diaz
Deposited On:04 Dec 2019 18:25
Last Modified:17 Mar 2020 16:12

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