Review of isomer properties

Isomers are long-lived excited states of atomic nuclei, with half-lives ranging up to many years. They arise due to unusual combinations of spin and shape. Spin isomers, in particular, are dependent on the behaviour of individual protons and neutrons in the nucleus, and they give basic nuclear structure information. The long half-lives enable accurate measurements of, for example, the shapes and sizes of excited nuclear states, providing sensitive tests of theoretical calculations. Historically, isomers have played, and continue to play, a key role in theoretical developments, for both spherical and non-spherical nuclei. A priority of UK nuclear physics today is the exploration and understanding of the limits to nuclear binding (at the so-called 'drip-lines' and for 'superheavy' elements). In this context, spin isomers have special importance, since they can provide extra stability for the most exotic, short-lived nuclei. This realization gives strong emphasis to the need to understand isomer properties, especially their half-lives. The visit of Professor G.D. Dracoulis (from the Australian National University, Canberra) will stimulate isomer physics in the UK through networking and giving talks, with a focus on the preparation of an isomer review article in collaboration with Professor P.M. Walker (at the University of Surrey, Guildford).