Beta-asymmetry studies on polarized 82Rb atoms in a TOP trap

Abstract

Atoms of 82Rb (t1/2 = 76 s) confined in a time-orbiting-potential (TOP) magnetic trap make a favorable source for β-asymmetry studies by providing an essentially massless source of highly polarized atoms. An offline mass separator is coupled to a double magneto-optical trap (MOT) and TOP trap system. Once in the TOP trap the magnetic trap's rotating bias field defines the polarization axis and allows one to measure the correlation between the nuclear spin direction and the β emission direction using a single positron detector. A proof-of-principle experiment using this method has demonstrated that the parity violating ( β → ⋅ J → ) correlation can be studied. Here we outline improvements to the experiment with the goal of a 1% measurement of the β-asymmetry correlation parameter A in the Gamow-Teller decay of 82Rb which in the semi-leptonic sector would pose a competitive test of the Standard Model.