Commissioning the Nab Experiment

High precision beta decay experiments with neutrons offer a set of stringent tests of the Standard Model, ranging from searches for new physics through tests of Cabibbo Kobayashi Maskawa (CKM) matrix unitarity to searches for exotic Scalar and Tensor couplings through measurements of a Fierz interference term. Unitarity tests are based on the extracted value for the V_ud matrix element, extracted from measurements of the axial coupling constant (λ) and the free neutron lifetime. The Nab experiment at the Spallation Neutron Source in Oak Ridge, Tennessee, aims to determine λ to relative uncertainty of ~0.03% and the Fierz term to absolute precision of 0.003. During the latest SNS beam cycle, we have taken the first commissioning run with a fully assembled apparatus. In this talk, I will provide an overview and status of the experiment, data from the commissioning run, and the future plans of the experiment.