We report an improved measurement of the free neutron lifetime $tau_{n}$ using the UCN$tau$ apparatus at the Los Alamos Neutron Science Center. We counted a total of approximately $38times10^{6}$ surviving ultracold neutrons (UCN) after storing in UCN$tau$s magneto-gravitational trap over two data acquisition campaigns in 2017 and 2018. We extract $tau_{n}$ from three blinded, independent analyses by both pairing long and short storage-time runs to find a set of replicate $tau_{n}$ measurements and by performing a global likelihood fit to all data while self-consistently incorporating the $beta$-decay lifetime. Both techniques achieve consistent results and find a value $tau_{n}=877.75pm0.28_{text{ stat}}+0.22/-0.16_{text{ syst}}$~s. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.
Download