Some atomic effects in β decay, with one application to astrophysics and one to elementary particle physics

This article is intended to be an introduction to some atomic effects on β decay in astrophysics and in elementary particle physics. The emphasis is on the development of physical insights rather than on rigor. Two limiting cases are of special interest. The first is low‐energy high‐Z β decay, for which atomic effects can be large, and the second is high‐energy low‐Z superallowed transitions, for which atomic effects are small but important because both theory and experiment are accurate to about 1 part in a thousand. The discussion of the low‐energy high‐Z domain includes a qualitative description of the β decay of 187Re and of its application to studies of the age of our solar system and of our galaxy. The extremely large bound‐state β‐decay rate of highly ionized 187Re, present in certain astrophysical environment, is of particular interest. We give a simplified derivation, applicable to any β decay in this domain, for both allowed and forbidden continuum decay, of overlap effects; these originate in t...