Abstract
Abstract The neutron lifetime has been measured by comparing the decay rate with the reaction rate of $^3$He nuclei of a pulsed neutron beam from the spallation neutron source at the Japan Proton Accelerator Research Complex (J-PARC). The decay rate and the reaction rate were determined by simultaneously detecting electrons from the neutron decay and protons from the $^3$He(n,p)$^3$H reaction using a gas chamber, the working gas of which contains diluted $^3$He. The measured neutron lifetime was $898\,\pm\,10\,_{\rm stat}\,^{+15}_{-18}\,_{\rm sys}\,$s.
Highlights
A neutron decays into a proton, an electron, and an antineutrino through the weak interaction
Electrons from the neutron decays are counted by observing the ionization tracks induced in the gas of a time projection chamber (TPC), because it is sensitive to electrons but not the observational data and the theoretical prediction for light element abundances provides a good opportunity to test cosmological models [1,2,3,4]
The neutron lifetime puzzle, the discrepancy of 8.5 s (4.0 σ ) between the experimental data obtained with the bottle and beam methods, is still unsolved
Summary
A neutron decays into a proton, an electron, and an antineutrino through the weak interaction. The. Big Bang Nucleosynthesis (BBN) is considered to create light elements, and the comparison of. Big Bang Nucleosynthesis (BBN) is considered to create light elements, and the comparison of In this experiment, electrons from the neutron decays are counted by observing the ionization tracks induced in the gas of a time projection chamber (TPC), because it is sensitive to electrons but not the observational data and the theoretical prediction for light element abundances provides a good opportunity to test cosmological models [1,2,3,4]. The neutron lifetime determines the number ratio of protons to neutrons at the beginning of the BBN, which affects the BBN yields of light elements, especially 4 He [5]
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