β-delayed neutron emission of r-process nuclei at the N = 82 shell closure

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

doi:10.1016/j.physletb.2021.136266

Abstract

Theoretical models of β-delayed neutron emission are used as crucial inputs in r-process calculations. Benchmarking the predictions of these models is a challenge due to a lack of currently available experimental data. In this work the β-delayed neutron emission probabilities of 33 nuclides in the important mass regions south and south-west of 132Sn are presented, 16 for the first time. The measurements were performed at RIKEN using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The P1n values presented constrain the predictions of theoretical models in the region, affecting the final abundance distribution of the second r-process peak at A≈130.

Highlights

The astrophysical conditions for the r-process, i.e. the nucleosynthesis process responsible for the production of half the elements heavier than iron, are still a matter of debate [1,2,3]
Heavy element abundance predictions are sensitive to the values of nuclear masses, β-decay half-lives and β-delayed neutron emission probabilities Pn of very neutron-rich nuclei [13,14]. r-process calculations are sensitive to Pn values of nuclei along the r-process path and of nuclei encountered as they β-decay back to stability, where neutron emission causes branching along the decay chains modifying the final abundance distributions and acts as a secondary source of neutrons during freeze-out
Nuclear theory predictions of Pn values depend on the βstrength function Sβ [15], and the masses of the nuclei used for the calculations

Summary

Introduction

The astrophysical conditions for the r-process, i.e. the nucleosynthesis process responsible for the production of half the elements heavier than iron, are still a matter of debate [1,2,3]. Heavy element abundance predictions are sensitive to the values of nuclear masses, β-decay half-lives and β-delayed neutron emission probabilities Pn of very neutron-rich nuclei [13,14].

Results

Conclusion