Acquisition of a Spectrometer and Detectors for Precision Nuclear Physics Measurements of Neutron Beta Decay

California Institute Of Technology, Pasadena CA

Investigators

Abstract

A superconducting solenoidal spectrometer and state-of-the-art detectors for low energy electrons will be used for a series of high precision measurements of neutron beta-decay using, for the first time, Ultra-Cold Neutrons (UCN). In particular the angular correlation (A) between the neutron spin direction and the electron momentum will be measured with a statistical precision of < 0.2% and substantially smaller systematic errors. This represents nearly a factor of five improvement over the present best measurements in an experiment with significantly different and considerably smaller systematic uncertainties. High-precision measurements of the A-correlation in neutron beta-decay can be combined with measurements of the neutron and muon lifetimes to extract the u-quark/d-quark weak mixing also known as V_ud - a key component of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. Improved measurements of V_ud can provide access to physics beyond the Standard Model by testing the unitarity of this matrix.