Can a stray static electric field mimic parity violation in Stark experiments on forbidden M1 transitions ?

Abstract

This paper deals with one aspect of the problem of systematic errors in experiments designed to test parity violation in forbidden M 1 radiative transitions (e.g. nS1/2-n'S 1/2 in Cs or nP1/2-n'P1/2 in Tl). A spurious signal can arise in presence of a stray static electric field ΔE which does not reverse with the voltage applied to the electrodes. For the experiments in progress the false asymmetry can only appear under the combined effect of this spurious field and of a geometrical misalignment of the set-up. We describe different procedure, using the atoms themselves as a probe, to test the magnitude of ΔE and of the misalignment, and to partially compensate these defects. Once such care is taken it seems to be possible to keep the systematics well below 10 % of the expected signal