Towards An Accurate Measurement of the Lifetime of Ultracold Neutrons Suspended in a Novel Fully Magnetic Trap

forthcoming

The Standard Model (SM) of Particle Physics predicts the free neutron lifetime, τn, as a function of only two input parameters with high precision. Recent theoretical progress now provides a SM description of neutron decay at the 10−4 level. My project, NuLife, will enable a future measurement of τn with 0.1 s accuracy to test these SM predictions at the same unprecedented level through the pioneering development of a novel, large-volume, and deep magnetic trap. Previous measurements with a material trap confirm that at least 200 times more ultracold neutrons (UCN) can be stored in such a deep magnetic trap, compared to our proof-of-principle setup τSPECT, when connected to the high-intensity UCN source of the Paul Scherrer Institute, Switzerland. My team and I will boost the statistical precision of the future experiment τSPECT2 by developing a novel phase-space matching beamline to maximize the transport of UCNs from the source to the trap. Complementary, we innovate large-scale hardware components required to fully exploit the superior control of systematic bias effects achievable in a fully magnetic trap and mandatory to determine τn with 0.1 s accuracy. My measurement will provide a high-precision test of the structure of the weak interaction which governs countless phenomena e.g., hydrogen fusion in stars and the radioactive decay of neutrons and nuclei. In theory, a much richer structure is allowed than yet experimentally observed: But nobody knows why Nature is as simple as it is! Tiny experimental departures from the SM prediction may hint at physics beyond the SM (BSM). Through its unprecedented accuracy on τn, my future experiment τSPECT2 will help to resolve experimental tensions in precision neutron decay observables and will enable high-sensitivity searches for new decay channels with the potential to either set very stringent limits on BSM models, or to discover new feeble interactions, new particles, and new structures of the weak interaction.