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arXiv · 1408.6173

Level densities and thermodynamical properties of Pt and Au isotopes

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

The nuclear level densities of $^{194-196}$Pt and $^{197,198}$Au below the neutron separation energy have been measured using transfer and scattering reactions. All the level density distributions follow the constant-temperature description. Each group of isotopes is characterized by the same temperature above the energy threshold corresponding to the breaking of the first Cooper pair. A constant entropy excess $ΔS=1.9$ and $1.1$ $k_B$ is observed in $^{195}$Pt and $^{198}$Au with respect to $^{196}$Pt and $^{197}$Au, respectively, giving information on the available single-particle level space for the last unpaired valence neutron. The breaking of nucleon Cooper pairs is revealed by sequential peaks in the microcanonical caloric curve.

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F. Giacoppo, F. L. Bello Garrote, L. A. Bernstein, D. L. Bleuel, T. K. Eriksen, R. B. Firestone, A. Görgen, M. Guttormsen, T. W. Hagen, B. V. Kheswa, M. Klintefjord, P. E. Koehler, A. C. Larsen, H. T. Nyhus, T. Renstrøm, E. Sahin, S. Siem, T. Tornyi. 2014-11-28. Level densities and thermodynamical properties of Pt and Au isotopes. https://doi.org/10.1103/physrevc.90.054330

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