β -Delayed One and Two Neutron Emission Probabilities Southeast of Sn132 and the Odd-Even Systematics in

V. H. Phong,S. Nishimura,G. Lorusso, T. Davinson, A. Estradé, O. Hall,Toshihiko Kawano,J. Liu, F. Montes,Nobuya Nishimura, R. Grzywacz,K. P. Rykaczewski, J. Agramunt,D. S. Ahn, A. Algora, J. M. Allmond, H. Baba, S. Bae,N. T. Brewer,Carlo Bruno, R. Caballero-Folch, F. Calviño, P.J. Coleman-Smith, G. Cortés, I. Dillmann, C. Domingo‐Pardo, A. Fijałkowska, N. Fukuda, S. Go, C. J. Griffin, J. H. Ha, L. J. Harkness-Brennan, T. Isobe, D. Kahl, L. H. Khiem, G. Kiss, A. Korgul, T. Kubo, M. Labiche, I. Lazarus,J. F. Liang,Z. Liu, K. Matsui, K. Miernik, B. Moon,Ana Isabel Morales, P. Morrall, N. Nepal,R. D. Page, M. Piersa-Siłkowska, V. Pucknell, B.C. Rasco, B. Rubio,H. Sakuraï, Y. Shimizu,D. W. Stracener,T. Sumikama,Hiroshi Suzuki,J. L. Taı́n,Hiroyuki Takeda, A. Tarifeño-Saldivia, A. Tolosa-Delgado, M. Wolińska-Cichocka, P. J. Woods,R. Yokoyama

The β-delayed one- and two-neutron emission probabilities (P_{1n} and P_{2n}) of 20 neutron-rich nuclei with N≥82 have been measured at the RIBF facility of the RIKEN Nishina Center. P_{1n} of ^{130,131}Ag, ^{133,134}Cd, ^{135,136}In, and ^{138,139}Sn were determined for the first time, and stringent upper limits were placed on P_{2n} for nearly all cases. β-delayed two-neutron emission (β2n) was unambiguously identified in ^{133}Cd and ^{135,136}In, and their P_{2n} were measured. Weak β2n was also detected from ^{137,138}Sn. Our results highlight the effect of the N=82 and Z=50 shell closures on β-delayed neutron emission probability and provide stringent benchmarks for newly developed macroscopic-microscopic and self-consistent global models with the inclusion of a statistical treatment of neutron and γ emission. The impact of our measurements on r-process nucleosynthesis was studied in a neutron star merger scenario. Our P_{1n} and P_{2n} have a direct impact on the odd-even staggering of the final abundance, improving the agreement between calculated and observed Solar System abundances. The odd isotope fraction of Ba in r-process-enhanced (r-II) stars is also better reproduced using our new data.