학술논문
The $^{59}$Fe(n, {\gamma})$^{60}$Fe Cross Section from the Surrogate Ratio Method and Its Effect on the $^{60}$Fe Nucleosynthesis
Document Type
Working Paper
Author
Yan, S. Q.; Li, X. Y.; Nishio, K.; Lugaro, M.; Li, Z. H.; Makii, H.; Pignatari, M.; Wang, Y. B.; Orlandi, R.; Hirose, K.; Tsukada, K.; Mohr, P.; Li, G. S.; Wang, J. G.; Gao, B. S.; Han, Y. L.; Guo, B.; Li, Y. J.; Shen, Y. P.; Sato, T. K.; Ito, Y.; Suzaki, F.; Su, J.; Yang, Y. Y.; Wang, J. S.; Ma, J. B.; Ma, P.; Bai, Z.; Xu, S. W.; Ren, J.; Fan, Q. W.; Zeng, S.; Han, Z. Y.; Nan, W.; Nan, W. K.; Chen, C.; Lian, G.; Hu, Q.; Duan, F. F.; Jin, S. Y.; Tang, X. D.; Liu, W. P.
Source
Subject
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Abstract
The long-lived $^{60}$Fe (with a half-life of 2.62 Myr) is a crucial diagnostic of active nucleosynthesis in the Milky Way galaxy and in supernovae near the solar system. The neutron-capture reaction $^{59}$Fe(n,$\gamma$)$^{60}$Fe on $^{59}$Fe (half-life = 44.5 days) is the key reaction for the production of $^{60}$Fe in massive stars. This reaction cross section has been previously constrained by the Coulomb dissociation experiment, which offered partial constraint on the $E$1 $\gamma$-ray strength function but a negligible constraint on the $M$1 and $E$2 components. In this work, for the first time, we use the surrogate ratio method to experimentally determine the $^{59}$Fe(n,$\gamma$)$^{60}$Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.5 $\pm$ 3.5 mb at $kT$= 30 keV and 13.4 $\pm$ 1.7 mb at $kT$= 90 keV, roughly 10 - 20% higher than previous estimates. We analyzed the impact of our new reaction rates in nucleosynthesis models of massive stars and found that uncertainties in the production of $^{60}$Fe from the $^{59}$Fe(n,$\gamma$)$^{60}$Fe rate are at most of 25%. We conclude that stellar physics uncertainties now play a major role in the accurate evaluation of the stellar production of $^{60}$Fe.
Comment: 9 pages with 6 figures
Comment: 9 pages with 6 figures