Direct cross-section measurement of the weak r-process 88Sr({\alpha},n)91Zr reaction in {\nu}-driven winds of core collapse supernovae
| Autor: | Fougères, C., Avila, M. L., Jayatissa, H., Santiago-Gonzalez, D., Brandenburg, K., Meisel, Z., Mohr, P., Montes, F., Műller-Gatermann, C., Neto, D., Ong, W. -J., Pereira, J., Rehm, K. E., Tang, T. L., Tolstukhin, I. A., Varriano, L., Wilson, G., Wu, J. |
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| Rok vydání: | 2024 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | About half of the heavy elements beyond iron are known to be produced by the rapid neutron capture process, known as r-process. However, the astrophysical site producing the r-process is still uncertain. Chemical abundances observed in several cosmic sites indicate that different mechanisms should be at play. For instance, the abundances around silver measured in a subset of metal-poor stars indicate the presence of a weak r-process. This process may be active in neutrino-driven winds of core collapse supernovae where (${\alpha}$,n) reactions dominate the synthesis of Z ~ 40 elements in the expelled materials. Scarcely measured, the rates of (${\alpha}$,n) reactions are determined from statistical Hauser-Feshbach calculations with ${\alpha}$-optical-model potentials, which are still poorly constrained. The uncertainties of the (${\alpha}$,n) reaction rates therefore make a significant contribution to the uncertainties of the abundances determined from stellar modeling. In this work, the $^{88}$Sr(${\alpha}$,n)$^{91}$Zr reaction which impacts the weak r-process abundances has been probed at astrophysics energy for the first time; directly measuring the total cross sections at astrophysical energies of 8.37 - 13.09 MeV in the center of mass (3.8 - 7.5 GK). Two measurements were performed at ATLAS with the electrically-segmented ionization chamber MUSIC, in inverse kinematics, while following the active target technique. The cross sections of this ${\alpha}$-induced reaction on $^{88}$Sr, located at the shell closure N = 50, have been found to be lower than expected, by a factor of 3, despite recent statistical calculations validated by measurements on neighboring nuclei. This result encourages more experimental investigations of (${\alpha}$,n) reactions, at N = 50 and towards the neutron-rich side, to further test the predictive power and reliability of such calculations. Comment: 9 pages, 6 conference |
| Databáze: | arXiv |
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