Measurement of the Free Neutron Lifetime using the Neutron Spectrometer on NASA's Lunar Prospector Mission

TL;DR

This study uses data from NASA's Lunar Prospector to measure the free neutron lifetime from space, achieving results consistent with laboratory values and improving modeling to reduce systematic uncertainties.

Contribution

It presents the second space-based measurement of the neutron lifetime, incorporating advanced modeling of elemental composition to mitigate systematic errors.

Findings

Measured neutron lifetime as 887 ± 14 (stat) +7/-3 (syst) seconds.

Extended space-based neutron lifetime measurements to planetary bodies.

Improved modeling reduces systematic uncertainties in space measurements.

Abstract

We use data from the Lunar Prospector Neutron Spectrometer to make the second space-based measurement of the free neutron lifetime finding $\tau_n=887 \pm 14_\text{stat}{\:^{+7}_{-3\:\text{syst}}}$ s, which is within 1$\sigma$ of the accepted value. This measurement expands the range of planetary bodies where the neutron lifetime has been quantified from space, and by extending the modeling to account for non-uniform elemental composition, we mitigated a significant source of systematic uncertainty on the previous space-based lifetime measurement. This modeling moves space-based neutron lifetime measurement towards the ultimate goal of reducing the magnitude of the systematics on a future space-measurement to the level of those seen in laboratory-based experiments.