Experiments on parity non-conservation in atoms

This article reviews the progress made over the last decade to observe and measure parity non-conserving effects in atomic phenomena, predicted on the basis of presently accepted gauge theories of the weak and electromagnetic interactions. The experiments on circular dichroism in caesium and thallium are described, also those on optical rotation in bismuth and lead; the most recent results are given and compared with theory. The present position is that there is strong evidence for parity non-conservation at the level predicted by the Weinberg-Salam theory but that more experimental and theoretical work is needed. Work on hydrogen is also described; no results have yet been reported for this element but the experiments are of particular interest because the atomic theory introduces negligible uncertainty. Prospects for the future are briefly reviewed. 49 refs., 9 fig., 1 tab. (author)