1. Quasicontinuum $\gamma$-decay of $^{91,92}$Zr: benchmarking indirect ($n,\gamma$) cross section measurements for the $s$-process
- Author
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Guttormsen, M., Goriely, S., Larsen, A. C., Görgen, A., Hagen, T. W., Renstrøm, T., Siem, S., Syed, N. U. H., Tagliente, G., Toft, H. K., Utsunomiya, H., Voinov, A. V., and Wikan, K.
- Subjects
Nuclear Experiment - Abstract
Nuclear level densities (NLDs) and $\gamma$-ray strength functions ($\gamma$SFs) have been extracted from particle-$\gamma$ coincidences of the $^{92}$Zr($p,p' \gamma$)$^{92}$Zr and $^{92}$Zr($p,d \gamma$)$^{91}$Zr reactions using the Oslo method. The new $^{91,92}$Zr $\gamma$SF data, combined with photonuclear cross sections, cover the whole energy range from $E_{\gamma} \approx 1.5$~MeV up to the giant dipole resonance at $E_{\gamma} \approx 17$~MeV. The wide-range $\gamma$SF data display structures at $E_{\gamma} \approx 9.5$~MeV, compatible with a superposition of the spin-flip $M1$ resonance and a pygmy $E1$ resonance. Furthermore, the $\gamma$SF shows a minimum at $E_{\gamma} \approx 2-3$~MeV and an increase at lower $\gamma$-ray energies. The experimentally constrained NLDs and $\gamma$SFs are shown to reproduce known ($n, \gamma$) and Maxwellian-averaged cross sections for $^{91,92}$Zr using the {\sf TALYS} reaction code, thus serving as a benchmark for this indirect method of estimating ($n, \gamma$) cross sections for Zr isotopes., Comment: 10 pages and 9 figures
- Published
- 2017
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