Qian, Y.-Z. and Haxton, W. C. and Langanke, K. and Vogel, P. (1997) Neutrino-induced neutron spallation and supernova r-process nucleosynthesis. Physical Review C, 55 (3). pp. 1532-1544. ISSN 0556-2813 http://resolver.caltech.edu/CaltechAUTHORS:QIAprc97
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It is quite likely that the site of the r process is the hot, neutron-rich “bubble” that expands off a protoneutron star during a core-collapse supernova. The r process would then occur in an intense flux of neutrinos. In order to explore the consequences of the neutrino irradiation, we calculate the rates of charged-current and neutral-current neutrino reactions on neutron-rich heavy nuclei, and estimate the average number of neutrons emitted in the resulting spallation. Our results suggest, for a dynamic r process occurring in an expanding bubble, that charged-current νe captures might help shorten the time scale for the r process, bringing it into better accord with our expectations about the conditions in the hot bubble: neutrino reactions can be important in breaking through the waiting-point nuclei at N=50 and 82, while still allowing the formation of abundance peaks. Furthermore, after the r process freezes out, there appear to be distinctive neutral-current and charged-current postprocessing effects. These include a spreading of the abundance peaks and damping of the most pronounced features (e.g., peaks and valleys) in the unpostprocessed abundance distribution. Most importantly, a subtraction of the neutrino postprocessing effects from the observed solar r-process abundance distribution shows that two mass regions, A=124–126 and 183–187, are inordinately sensitive to neutrino postprocessing effects. This imposes very stringent bounds on the freeze-out radii and dynamic time scales governing the r process. Moreover, we find that the abundance patterns within these mass windows are entirely consistent with synthesis by neutrino interactions. This strongly argues that the r process must occur in the intense neutrino flux provided by a core-collapse supernova. It also greatly restricts dynamic models for the supernova r-process nucleosynthesis.
|Additional Information:||©1997 The American Physical Society Received 5 November 1996 We thank George Fuller, Brad Meyer, and Friedel Thielemann for helpful discussions, and especially thank George Fuller and Gail McLaughlin for comments that helped us in improving this paper. Y.-Z. Qian and P. Vogel acknowledge the Institute for Nuclear Theory at University of Washington, Seattle for its hospitality during the time part of this work was done. This work was supported by the Department of Energy under Grant Nos. DE-FG06-96ER40561 and DEFG03-88ER-40397, and by the National Science Foundation under Grant Nos. PHY94-12818 and PHY94-20470. Y.-Z. Qian was supported by a grant at Caltech.|
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