UCNtau+ a Next Generation Neutron Lifetime Experiment

Precise measurement of the neutron lifetime is critical to understanding the Standard Model. The neutron lifetime is one of two inputs for beta decay precision tests of the unitarity of the SM CKM matrix. UCNtau has provided the most precise measurement of the neutron lifetime to date. UCNtau traps ultracold neutrons in a magneto-gravitational trap and then counts them by lowering a neutron detector into the trap. Using this method, UCNtau has achieved an uncertainty of ~0.3 seconds. Its upgrade, UCNtau+, aims to reduce the neutron lifetime measurement uncertainty to ~0.1 seconds. One improvement of UCNtau+ is the addition of an elevator to adiabatically lower neutrons into the trap. Using this technique, the neutron counting statistics can be increased by a factor of ~10. To accommodate this greater number of neutrons, further upgrades will be made to UCNTau's high-counting-rate detector. In this talk I will give an overview of the experiment and share preliminary results.