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Published October 15, 2021 | Accepted Version + Published
Journal Article Open

Improved Neutron Lifetime Measurement with UCNτ

Abstract

We report an improved measurement of the free neutron lifetime τ_n using the UCNτ apparatus at the Los Alamos Neutron Science Center. We count a total of approximately 38 × 10⁶ surviving ultracold neutrons (UCNs) after storing in UCNτ's magnetogravitational trap over two data acquisition campaigns in 2017 and 2018. We extract τ_n from three blinded, independent analyses by both pairing long and short storage time runs to find a set of replicate τ_n measurements and by performing a global likelihood fit to all data while self-consistently incorporating the β-decay lifetime. Both techniques achieve consistent results and find a value τ_n = 877.75 ± 0.28_(stat) + 0.22/−0.16_(syst) s. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.

Additional Information

© 2021 American Physical Society. (Received 18 June 2021; accepted 20 July 2021; published 13 October 2021) This work is supported by the LANL LDRD program; the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Awards No. DE-FG02-ER41042, No. DE-AC52-06NA25396, No. DE-AC05-00OR2272, and No. 89233218CNA000001 under proposal LANLEEDM; NSF Grants No. 1614545, No. 1914133, No. 1506459, No. 1553861, No. 1812340, No. 1714461, and No. 1913789; and NIST precision measurements grant.

Attached Files

Published - PhysRevLett.127.162501.pdf

Accepted Version - 2106.10375.pdf

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Additional details

Created:
August 20, 2023
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