Half-lives and branchings for {\beta}-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process

P. Hosmer; H. Schatz; A. Aprahamian; O. Arndt; R. R. C. Clement; A. Estrade; K. Farouqi; K. -L. Kratz; S. N. Liddick; A. F. Lisetskiy; P. F. Mantica; P. Möller; W. F. Mueller; F. Montes; A. C. Morton; M. Ouellette; E. Pellegrini; J. Pereira; B. Pfeiffer; P. Reeder; P. Santi; M. Steiner; A. Stolz; B. E. Tomlin; W. B. Walters; A. Wöhr

doi:10.1103/physrevc.82.025806

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arXiv · 1011.5255

Half-lives and branchings for {\beta}-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process

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Abstract

The {\beta} decays of very neutron-rich nuclides in the Co-Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL {\beta}-counting station in conjunction with the neutron detector NERO. We measured the branchings for {\beta}-delayed neutron emission (Pn values) for 74Co (18 +/- 15%) and 75-77Ni (10 +/- 2.8%, 14 +/- 3.6%, and 30 +/- 24%, respectively) for the first time, and remeasured the Pn values of 77-79Cu, 79,81Zn, and 82Ga. For 77-79Cu and for 81Zn we obtain significantly larger Pn values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of 75Co (30 +/- 11 ms) and 80Cu (170+110 -50 ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process (r-process) is explored. We find that with our new data, the classical r-process model is better able to reproduce the A = 78-80 abundance pattern inferred from the solar abundances. The new data also influence r-process models based on the neutrino-driven high-entropy winds in core collapse supernovae.

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P. Hosmer, H. Schatz, A. Aprahamian, O. Arndt, R. R. C. Clement, A. Estrade, K. Farouqi, K. -L. Kratz, S. N. Liddick, A. F. Lisetskiy, P. F. Mantica, P. Möller, W. F. Mueller, F. Montes, A. C. Morton, M. Ouellette, E. Pellegrini, J. Pereira, B. Pfeiffer, P. Reeder, P. Santi, M. Steiner, A. Stolz, B. E. Tomlin, W. B. Walters, A. Wöhr. 2010-11-23. Half-lives and branchings for {\beta}-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process. https://doi.org/10.1103/physrevc.82.025806

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