Our present knowledge of atomic nuclei suggests that some 6000 to 7000 distinct nuclear species live long enough to be created and studied. Today we have learned something experimentally about roughly half of them. In essence we have two main ways of studying their properties, namely reactions and radioactive decay. The former has the attraction of flexibility and versatility. The latter is inflexible since nuclear decay is essentially God-given but it often provides the first means of identifying a new species and learning about its properties. Amongst all the possible decay modes of nuclei, beta decay is the most common across the table of nuclides.

Beta decay studies are especially interesting far from the line of stability where the Q-beta values are large and hence many states are energetically accessible in the daughter nucleus. However it is in just these very interesting cases where beta decay probabilities are most difficult to determine experimentally. The reason is the "Pandemonium Effect", which introduces systematic errors in measurements carried out with standard techniques.

In this colloquium I will introduce the Total Absorption Spectroscopy (TAS) technique, a remedy against "Pandemonium". I will present applications of the method to several problems of very different kind. It has allowed the first clear observation of the Gamow-Teller Resonance in beta decay, the deduction of the shape of the ground state of a nucleus from a study of its beta decay and the solution of part of the long standing discrepancy in the gamma component of the decay heat in reactors.

Argonne Physics Division Colloquium Schedule