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The beta strength function has been calculated for ~ 6 000 nuclei between the line of beta stability and the neutron drip line. The calculations -performed by using a schematical Brown-Bolsterli model -yield more reliable beta decay half lives, P, values and/?-delayed fission rates than the strongly oversimplified assumptions on S~ used up to now in astrophysical calculations. The calculated beta rates are shown in this paper to be decisive in the discussion of the problem of the astrophysical site of the r-process, which is responsible for the production of the heavy elements in the universe. In particular we concentrate on the neutron capture processes during the explosive burning of He in massive stars, initiated by the outgoing shock wave from a supernova explosion. It is shown that as consequence of the revised fi-decay rates explosive He-burning represents a very convincing alternative scenario to the classical r-process, which avoids the presently existing problems of the latter: 1. The computed relative abundances of r-nuclei resemble on the average their solar system counterparts. 2. The calculated abundance peaks essentially coincide in position with the observed ones. 3. The new site of the r-process avoids the problems of overproduction of heavy elements and of the mass-cut. Our results are based on realistic stellar models and hydrodynamical explosion calculations which for the first time are applied here to the problem of heavy element nucleosynthesis. The results turn out to be rather insensitive to the details of those models. The shorter/3-decay half lives obtained are of importance also in the investigation of further astrophysical sites producing heavy elements such as the n-processes in explosive C or Ne burning.

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Calculations of the neutrino capture cross sections for 69 'Ga based on a microscopic treatment of the Gamow-Teller matrix elements are presented. A strong enhancement of the cross section for highly energetic neutrinos is found compared to previous phenomenological estimates. As a consequence, the present assumptions on the signal from sB neutrinos in "Ga have to be revised. A nonnegligible solar model dependent background of 88 neutrinos has to be expected in a gallium solar neutrino experiment together mth the pp signal. The calculations yield a larger sensitivity of the gallium detector than assumed previously for galactic neutrinos.