Improved Neutron Lifetime Measurement with UCN$$\tau$$
- Indiana Univ., Bloomington, IN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- California Institute of Technology (CalTech), Pasadena, CA (United States)
- North Carolina State Univ., Raleigh, NC (United States); Duke Univ., Durham, NC (United States). Triangle Universities Nuclear Laboratory
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Indiana Univ., Bloomington, IN (United States)
- Inst. Laue-Langevin (ILL), Grenoble (France)
- Tennessee Technological Univ., Cookeville, TN (United States)
- DePauw Univ., Greencastle, IL (United States)
- East Tennessee State Univ. (ETSU), Johnson CIty, TN (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Joint Inst. for Nuclear Research (JINR), Dubna (Russian Federation)
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:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP); National Science Foundation (NSF); USDOE Laboratory Directed Research and Development (LDRD) Program
- Contributing Organization:
- UCNτ Collaboration
- Grant/Contract Number:
- AC05-00OR22725; FG02-ER41042; AC52-06NA25396; 89233218CNA000001; 1614545; 1914133; 1506459; 1553861; 1812340; 1714461; 1913789; AC05-00OR2272
- OSTI ID:
- 1899842
- Alternate ID(s):
- OSTI ID: 2000919
- Report Number(s):
- LA-UR-21-24910; TRN: US2311007
- Journal Information:
- Physical Review Letters, Vol. 127, Issue 16; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
atomic
nuclear and particle physics
neutron lifetime ultra cold neutrons UCN
beta decay
hadronic decays
leptonic
semileptonic & radiative decays
neutron physics
nuclear tests of fundamental interactions
magnetic mirrors & traps
neutrons
polarization
precision measurements
scintillators