A next generation neutron lifetime experiment based on UCNτ

The UCNτ 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 [1]; it is expected to ultimately reach a total uncertainty of about 0.2 s.  To achieve even better precision in follow-on experiments, at the 0.1 s level and beyond, the leading sources of uncertainty, including counting statistics, vibrational heating of the stored neutrons, evolution of the stored neutron population in phase space, rate-dependent counting efficiency effects, and depolarization of stored neutrons, must be addressed.  In this talk, we will discuss strategies for how to reduce these sources of uncertainty to achieve a total uncertainty on the neutron lifetime well below 0.1 s in future experiments based on the UCNτ concept, including increasing the storage volume, the strength of the confining magnetic field, or both.

[1] R. W. Pattie Jr. et al., Science 10.1126/science.aan8895 (2018).