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Abstract |
The beta-decay half-lives of 110 neutron-rich isotopes of the elements from 37 Rb to 50 Sn were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r-process calculations and reinforce the notion that the second (A approximate to 130) and the rare-earth-element (A approximate to 160) abundance peaks may result from the freeze-out of an (n, gamma) reversible arrow (gamma, n) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r-process events. |
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Address |
[Lorusso, G.; Nishimura, S.; Xu, Z. Y.; Shimizu, Y.; Soederstroem, P. -A.; Watanabe, H.; Browne, F.; Doornenbal, P.; Gey, G.; Taprogge, J.; Vajta, Zs.; Wu, J.; Baba, H.; Fukuda, N.; Inabe, N.; Isobe, T.; Kameda, D.; Kubo, T.; Sakurai, H.; Schury, P.; Suzuki, H.; Takeda, H.] RIKEN, Nishina Ctr, Wako, Saitama 3510198, Japan |
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