1NN 1NN B- HALF-LIFE:XUNDL-1 2016LE17 201612 1NN c Compiled (unevaluated) dataset from 2016Le17: 1NN c Phys Rev C 94, 045502 (2016) 1NN c Compiled by B. Singh (McMaster); Dec 26, 2016 1NN c 2016Le17: neutron lifetime measurement by method of storage of 1NN2c ultracold neutrons (UCN) in magneto-gravitational traps (magnetic 1NN3c bottle) and measuring the loss rate of neutrons using the 1.3-T Halbach 1NN4c octupole permanent (HOPE) magnet array aligned vertically at the 1NN5c Institut Laue-Langevin (ILL) in Grenoble. Three arrangements were used: 1NN6c with no UCN remover, with the UCN remover inserted for 80 s at 80 cm 1NN7c and 65 cm from the bottom of the trap, thus obtaining three values for 1NN8c the half-life of neutron. Details of the systematic uncertainties are 1NN9c discussed by authors. The results reported by 2016Le17 are from 1NNAc first-phase measurements with the HOPE system. 1NN L 0 1/2+ 615 S 27 1NN cL T$from |t=887 s {I39} (2016Le17, weighted average 1NN2cL of the two meanlife measurements by combining the statistical and 1NN3cL systematic uncertainties in quadrature: |t=895 s {I36} (stat) {I+42-45} 1NN3cL (syst) for the 65-cm remover, 881 s {I32} (stat) {I+33-42} (syst) for 1NN4cL the 80-cm remover. Value for no remover was |t=752 s {I19} (stat) 1NN5cL {I+29-36}, which is in disagreement with the recommended value 1NN6cL of |t{-n}=880.2 s {I10} (2016Pa37: Chinese Physics C 1NN7cL 40, 100001: PDG evaluation) by about 3.5|s 1NN 1NN B-:HALF-LIFE:XUNDL-2 2020WI07 202106 1NN c Compiled (unevaluated) dataset from 2020Wi07: 1NN c Physical Review Research 2, 023316 (2021) 1NN c Compiled by B. Singh (McMaster); June 05, 2021 1NN c First estimate of neutron mean lifetime from space-based observations, 1NN2c although, the analysis reported in the presented work was not based 1NN3c on an optimized measurement technique for the lifetime of the free 1NN4c neutron, as the main mission of these flybys was characterization of 1NN5c the composition of surfaces of Mercury and Venus, not the measurement 1NN6c of lifetime of neutron. 1NN c 2020Wi07: mean lifetime of free neutron estimated from analysis of 1NN2c measured variation of thermal neutron flux as a function of distance 1NN3c from the atmosphere of a planet, in this case in 2007-2008 flyby 1NN4c missions of Venus and Mercury by NASA's MESSENGER spacecraft, which 1NN5c carried a neutron spectrometer (NS) consisting of 10{+3} cm{+3} 1NN6c cube of a borated plastic scintillator sandwiched between two 1NN7c 4-mm-thick, 100 cm{+2} Li-glass detectors, the latter sensitive to 1NN8c thermal neutrons via {+6}Li+n|){+3}H+{+4}He reactions. High-energy 1NN9c neutrons in planetary atmospheres are generated in spallation reactions 1NNAc as a result of bombardment of nuclei in the atmosphere by high-energy 1NNBc protons present in galactic cosmic rays (GCRs). Through successive 1NNCc collisions, the high-energy neutrons ultimately reach thermal 1NNDc equilibrium with the atmosphere or a solid surface of a planet. The 1NNEc energy distribution of neutrons that escape from a planet into space is 1NNFc characteristic of the elemental composition of the planet on depth 1NNGc scales which are of the order of the neutron mean free path. 1NNHc In MESSENGER's flyby of Venus, the mean time of flight for detected 1NNIc neutrons varied between 80 and 640 s. The MESSENGER sampled neutron 1NNJc fluxes of Venus and Mercury at all altitudes above the closest 1NNKc approach during the flybys: 339 km for Venus, and 205 km for Mercury. 1NN L 0 1/2+ 541 S 92 1NN cL T$from estimated mean lifetime |t=780 s {I60}(stat) {I70}(syst) 1NN2cL (2020Wi07); the statistical and systematic uncertainties combined in 1NN3cL quadrature by compiler. 1NN4cL Analysis of mean lifetime of neutron used a set of models based on 1NN5cL different lifetimes for the data measured at Mercury and Venus, along 1NN6cL with surface or atmospheric composition and the planet's mass, which & 1NN7cL determines the rate at which the neutron flux decreases with increasing 1NN8cL distance from the planets. The estimated mean lifetime in the present 1NN9cL work can be compared with currently recommended (by the Particle Data 1NNAcL Group) mean lifetime |t=879.4 s {I6} from the UCN (bottle) method or 1NNBcL |t=879.6 s {I8}, if the measurement by neutron beam method is also 1NNCcL included in the averaging procedure (2020Zy02: Prog. Theor. Exp. Phys. 1NNDcL 2020, 083C01) or https://pdg.lbl.gov, where the evaluation has been 1NNEcL updated to 2021. 1NN 1NN B-:HALF-LIFE:XUNDL-3 2025Mu06 202505 1NN c Compiled (unevaluated) dataset from 2025Mu06: 1NN c Phys. Rev. C 111, 045501 (2025) 1NN c Compiled by E.A. McCutchan (NNDC,BNL) April 22, 2025 1NN c Measurement of neutron mean lifetime using magneto-gravitational trap 1NN c Measurement performed at the Los Alamos Ultracold Neutron Facility at 1NN2c LANL from the UCN|t experiment. Data here are collected for 1NN3c an additional three years beyond the initial measurement which 1NN4c occurred from 2017-2018. The current experiment used improved 1NN5c monitor detectors, reduced the necessary correction for 1NN6c UCN upscattering on residual gas and employed 4 different UCN detector 1NN7c geometries. 1NN L 0 1/2+ 608.47 S 21 1NN cL T$from mean lifetime |t=877.83 s {I22}(stat) {I+20-17}(syst) (2025Mu06) 1NN2cL with the statistical and systematic uncertainties combined in 1NN3cL quadrature by compiler. Result is for all data collected from 1NN4cL 2017, 2018, 2020, 2021 and 2022.