Abstract
Here we publish three years of data from the UCNτ experiment performed at the Los Alamos Ultracold Neutron Facility at the Los Alamos Neutron Science Center. These data are in addition to our previously published data. Our goals in this paper are to better understand and quantify systematic uncertainties and to improve the lifetime statistical precision. We previously reported a value from our 2017-2018 data for the neutron lifetime of 877.75±0.28 (statistical) +0.22-0.16 (systematic) s. We have collected an additional three years of data reported here for the first time. When all the data from UCNτ are averaged for 2017, 2018, 2020, 2021, and 2022, we report an updated value for the lifetime of 877.83±0.22 (statistical)+0.20-0.17 (systematic) s. We utilized improved monitor detectors, reduced our correction due to UCN upscattering on residual gas, and employed four different UCN detector geometries both to reduce the correction required for rate dependence and to explore potential contributions due to phase space evolution.
| Original language | English |
|---|---|
| Article number | 045501 |
| Journal | Physical Review C |
| Volume | 111 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 2025 |
Funding
The authors thank the staff and management of the Los Alamos Neutron Science Center for providing the UCN used for these experiments and the Los Alamos 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. 1553861, No. 2310015, No. 1812340, No. 1714461, No. 2110898, No. 1913789, No. 2209521, No. 2209481 and No. 2210341.