This award supports a collaborative program of research with Helio Dias of the University of Sao Paulo and Laercio Losano of the Federal University of Paraiba in Brazil and Francisco Krmpotic of the University of La Plata in Argentina collab- orating with G. E. Brown and T. T. S. Kuo of the State University of New York at Stony Brook. This program will calculate and estimate rates of weak interaction relevant to the evolution of stars, also rates of two-neutrino and neutrinoless double beta decays. The best available two-body matrix elements of the nucleon-nucleaon interaction will be used in various large shell model calculations. In the case of stellar evolution, one of the objectives is to obtain rates for transitions between excited states of the relevant nuclei. This project will bring the Brazilian and Argentinian work into contact with the best effective nuclear interactions and provide an improved calculation of electron capture rates and beta decays in stellar evolution, as well as double beta decay. The principal investigators in Brazil and Argentina are well experienced in shell-model and number-projected calculations while the Stony Brook side has had considerable experience in stellar evolution, electron capture and single and double beta decays. On the U.S. side, Stony Brook graduate students M. Aufderheide and D. B. Stout are already involved in this work. Other graduate students will be brought in. Besides the Brazilian and Argentinean principals, a successful research program will certainly influence postdoctoral and postgraduate research in the Universities of Sao Paulo, Paraiba and La Plata.
