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Improved Neutron Lifetime Measurement With Ucn Τ, Alexander Komives, Et Al.
Improved Neutron Lifetime Measurement With Ucn Τ, Alexander Komives, Et Al.
Physics & Astronomy Faculty publications
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/−0.16syst s. …
Measurement Of The Neutron Decay Electron-Antineutrino Angular Correlation By The Acorn Experiment, Alexander Komives, Et Al.
Measurement Of The Neutron Decay Electron-Antineutrino Angular Correlation By The Acorn Experiment, Alexander Komives, Et Al.
Physics & Astronomy Faculty publications
The aCORN experiment measures the neutron-decay electron-antineutrino correlation (a coefficient) using a novel method based on an asymmetry in proton time-of-flight for events where the beta electron and recoil proton are detected in delayed coincidence. We report the data analysis and result from the second run at the NIST Center for Neutron Research, using the high-flux cold neutron beam on the new NG-C neutron guide end position: a=−0.10758±0.00136(stat)±0.00148(sys). This is consistent within uncertainties with the result from the first aCORN run on the NG-6 cold neutron beam. Combining the two aCORN runs, we obtain a=−0.10782±0.00124(stat)±0.00133(sys), which has an overall relative …