Observation of double pygmy resonances in $^{195,196}$Pt and enhanced astrophysical reaction rates

F. Giacoppo; F. L. Bello Garrote; T. K. Eriksen; A. Görgen; M. Guttormsen; T. W. Hagen; A. C. Larsen; B. V. Kheswa; M. Klintefjord; P. E. Koehler; H. T. Nyhus; T. Renstrøm; E. Sahin; S. Siem; T. G. Tornyi

arXiv · 1402.2451

Observation of double pygmy resonances in $^{195,196}$Pt and enhanced astrophysical reaction rates

F. Giacoppo·F. L. Bello Garrote·T. K. Eriksen·A. Görgen·M. Guttormsen·T. W. Hagen·A. C. Larsen·B. V. Kheswa·M. Klintefjord·P. E. Koehler·H. T. Nyhus·T. Renstrøm·E. Sahin·S. Siem·T. G. Tornyi

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Abstract

Our measurements of $^{195,196}$Pt $\gamma$-strength functions show a double-humped enhancement in the $E_{\gamma}= 4-8$ MeV region. For the first time, the detailed shape of these resonances is revealed for excitation energies in the quasicontinuum. We demonstrate that the corresponding neutron-capture cross sections and astrophysical reaction rates are increased by up to a factor of 2 when these newly observed pygmy resonances are included. These results lend credence to theoretical predictions of enhanced reaction rates due to such pygmy resonances and hence are important for a better understanding of r-process nucleosynthesis.

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F. Giacoppo, F. L. Bello Garrote, T. K. Eriksen, A. Görgen, M. Guttormsen, T. W. Hagen, A. C. Larsen, B. V. Kheswa, M. Klintefjord, P. E. Koehler, H. T. Nyhus, T. Renstrøm, E. Sahin, S. Siem, T. G. Tornyi. 2014-02-11. Observation of double pygmy resonances in $^{195,196}$Pt and enhanced astrophysical reaction rates. https://arxiv.org/abs/1402.2451

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