New Possibilities of Measuring the Ratio of Axial-Vector Weak Interaction Constants

An experiment is being developed to determine the λ value (the ratio of the axial weak interaction constant G A to the vector constant G V ) by a simultaneous measurement of electron ( A ) and neutrino ( B ) β‑decay asymmetries using the same setup. The λ measurement is based on the ratio: λ = ( A – B )/( A + B ). The simultaneous measurement of A and B on the same setup is recommended to be carried out using ultracold neutrons stored in the magnetic field of a superconducting solenoid. The proposed method for determining λ, firstly, makes it possible to disregard the contribution of the Fierz interference term, and, secondly, eliminates the necessity of accurate measurement of the neutron polarization. The presented method allows one to measure the λ value with an accuracy of 10 –4 .