Status of the Analysis of the UCNτ Neutron Lifetime Experiment

The UCNτ experiment at the Los Alamos Neutron Science Center has provided the most precise measurement of the neutron lifetime. Neutron beta decay is the simplest type of beta decay, and a precise measurement of the neutron lifetime provides a useful way to probe the Standard Model, particularly by helping to determine V_ud, which can be used to test the unitarity of the CKM matrix. In the UCNτ experiment, ultracold neutrons are stored in a magneto-gravitational bottle and later counted in-situ by a Zinc Sulfide alpha detector coated with enriched ¹⁰B in order to extract the neutron lifetime. The methods and status of the analysis for the now unblinded data taken from 2020 to 2022 will be presented. There are different configurations of the experiment which have differing sensitivity to rate dependent effects, and the analysis consists of multiple blinded independent analyses. After completing evaluation of a newly-characterized systematic effect made possible by an upgrade to our primary detector, we will have a new measurement which is expected to further improve the overall experimental precision with which the free neutron lifetime is determined.