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Improved Neutron Lifetime Measurement with UCNτ

F. M. Gonzalez et al. (UCNτ Collaboration)
Phys. Rev. Lett. 127, 162501 – Published 13 October 2021
Physics logo See Viewpoint: Measuring the Neutron Lifetime with Record-Breaking Precision

Abstract

We report an improved measurement of the free neutron lifetime τn 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 τn from three blinded, independent analyses by both pairing long and short storage time runs to find a set of replicate τn 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 τn=877.75±0.28stat+0.22/0.16systs. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.

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  • Received 18 June 2021
  • Accepted 20 July 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.162501

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Nuclear Physics

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Measuring the Neutron Lifetime with Record-Breaking Precision

Published 13 October 2021

An improved version of a “bottle” experiment lets researchers lower the uncertainty on this important parameter—but a tantalizing discrepancy remains.

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Vol. 127, Iss. 16 — 15 October 2021

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