A next generation neutron lifetime measurement based on UCN$\tau $*

The UCN$\tau $ experiment measures the free neutron lifetime by in situ counting of surviving ultracold neutrons after different storage times in an asymmetric magneto-gravitational storage volume.~ This experiment has acquired sufficient data for a measurement of the neutron lifetime with a statistical uncertainty of about 0.35 s and has demonstrated a systematic uncertainty of 0.28 s; it is expected to ultimately reach a total uncertainty of about 0.2 s.~ To achieve even better precision, the leading sources of uncertainty, which include counting statistics, microphonic heating of the stored neutrons, evolution of the neutron population in phase space, counting rate-dependent effects, and interactions with the residual gas in the storage volume, must be addressed.~ In this talk, we will discuss how to reduce these sources of uncertainty to achieve a total uncertainty on the neutron lifetime well below 0.1 s in the second generation Tau2 experiment.