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Improved Neutron Lifetime Measurement with UCN$$\tau$$

Journal Article · · Physical Review Letters
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  1. Indiana Univ., Bloomington, IN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. California Institute of Technology (CalTech), Pasadena, CA (United States)
  3. North Carolina State Univ., Raleigh, NC (United States); Duke Univ., Durham, NC (United States). Triangle Universities Nuclear Laboratory
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Argonne National Lab. (ANL), Argonne, IL (United States)
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  7. Indiana Univ., Bloomington, IN (United States)
  8. Inst. Laue-Langevin (ILL), Grenoble (France)
  9. Tennessee Technological Univ., Cookeville, TN (United States)
  10. DePauw Univ., Greencastle, IL (United States)
  11. East Tennessee State Univ. (ETSU), Johnson CIty, TN (United States)
  12. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  13. Joint Inst. for Nuclear Research (JINR), Dubna (Russian Federation)
+ Show Author Affiliations
In this work, we report an improved measurement of the free neutron lifetime $$\tau_n$$ using the UCN$$\tau$$ apparatus at the Los Alamos Neutron Science Center. We count a total of approximately 38×106 surviving ultracold neutrons (UCNs) after storing in UCN$$\tau$$’s magnetogravitational trap over two data acquisition campaigns in 2017 and 2018. We extract $$\tau$$n from three blinded, independent analyses by both pairing long and short storage time runs to find a set of replicate $$\tau$$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 $$\tau$$n=877.75±0.28stat+0.22/–0.16syst 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.
Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC), Nuclear Physics (NP)
Contributing Organization:
UCNτ Collaboration
Grant/Contract Number:
89233218CNA000001; AC05-00OR22725; AC52-06NA25396
OSTI ID:
1899842
Alternate ID(s):
OSTI ID: 2000919
Report Number(s):
LA-UR--21-24910
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 16 Vol. 127; ISSN 0031-9007
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
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