Neutron lifetime measurement with pulsed cold neutrons

TL;DR

This paper reports a measurement of the neutron lifetime using pulsed cold neutrons at J-PARC, employing simultaneous detection of decay electrons and reaction protons to determine the lifetime with quantified uncertainties.

Contribution

It introduces a novel experimental method combining decay and reaction rate measurements with pulsed cold neutrons for precise neutron lifetime determination.

Findings

Measured neutron lifetime: 898 ± 10 (stat) +15/-18 (sys) seconds.

Utilized simultaneous detection of decay electrons and reaction protons.

Demonstrated a new approach for neutron lifetime measurement.

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 of which working gas contains diluted $^3$He. The measured neutron lifetime was $898\,\pm\,10\,_{\rm stat}\,^{+15}_{-18}\,_{\rm sys}\,$s.