Strong one-neutron emission from two-neutron unbound states in 
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 decays of the 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>r</mml:mi></mml:math>
-process nuclei 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">Ga</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>86</mml:mn><mml:mo>,</mml:mo><mml:mn>87</mml:mn></mml:mrow></mml:mmultiscri

Yokoyama, R.; Grzywacz, R.; Rasco, B. C.; Brewer, N. T.; Rykaczewski, K. P.; Dillmann, I.; Taín, J. L.; Nishimura, S.; Ahn, D. S.; Algora, A.; Allmond, J. M.; Agramunt, J.; Baba, H.; Bae, S.; Bruno, Carlo; Caballero-Folch, R.; Calviño, F.; Coleman-Smith, P.J.; Cortés, G.; Davinson, T.; Domingo‐Pardo, C.; Estradé, A.; Fukuda, N.; Go, S.; Griffin, C. J.; Ha, J. H.; Hall, O.; Harkness-Brennan, L. J.; Heideman, J.; Isobe, T.; Kahl, D.; Karny, M.; Kawano, Toshihiko; Khiem, L. H.; King, T. T.; Kiss, G. G.; Korgul, A.; Kubo, T.; Labiche, M.; Lazarus, I.; Liang, J. F.; Liu, J.; Lorusso, G.; Madurga, M.; Matsui, K.; Miernik, K.; Montes, F.; Morales, Ana Isabel; Morrall, P.; Nepal, N.; Page, R. D.; Phong, V. H.; Prydderch, M.; Pucknell, V.; Rajabali, M. M.; Rubio, B.; Saito, Yoshihiko; Sakuraï, H.; Shimizu, Y.; Simpson, John; Singh, M.; Stracener, D. W.; Sumikama, T.; Surman, Rebecca; Suzuki, Hiroshi; Takeda, Hiroyuki; Tarifeño-Saldivia, A.; Thomas, S.L.; Tolosa-Delgado, A.; Wolińska-Cichocka, M.; Woods, P. J.; Xu, Xinxin

doi:10.1103/physrevc.100.031302

Cited by 16 publications

(3 citation statements)

References 34 publications

(64 reference statements)

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“…Study of neutron-rich nuclei around N=126, called ′ blank spot ′ nuclei, is in progress by multinucleon transfer reactions [168,169,170,171]. Another important nuclear physics input, the β-delayed neutron emission probability, is also under investigation in several facilities of the world [172,173,174,175,176,177].…”

Section: Discussionmentioning

confidence: 99%

“…Recently a systematic measurement of the one-and multi-neutron emission probabilties in neutron-rich nuclei started at RIKEN, using a high-efficiency array of 3 He neutron countors (BRIKEN) [172], though there had been a number of experimental works [173,174,175,176]. For example β-delayed one-and two-neutron branching ratios (P 1n and P 2n ) have been measured in the r-process nuclei 86,87 Ga at RIBF, RIKEN [177,172]. An extension of the present shell-model study on half-lives of N =126 isotones to nuclei in the ′ blank spot ′ region and evaluation of neutron emission probabilities is a challenging future problem.…”

Section: β-Decay Rates For N =126 Isotones For R-process Nucleosynthesismentioning

confidence: 99%

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Nuclear Weak Rates and Nuclear Weak Processes in Stars

Suzuki

2022

Preprint

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Nuclear weak rates in stellar environments are obtained by taking into account recent advances in shell-model studies of spin-dependent excitation modes in nuclei including Gamow-Teller (GT) and spin-dipole transitions. They are applied to nuclear weak processes in stars such as cooling and heating of the cores of stars and nucleosynthesis in supernovae. The important roles of accurate weak rates for the study of astrophysical processes are pointed out in the following cases. (1) The electron-capture (e-capture) and β-decay rates in sd-shell are evaluated with the USDB Hamiltonian and used to study the evolution of O-Ne-Mg cores in stars with 8-10 M ⊙ . The important roles of the A =23 and 25 pairs of nuclei for the cooling of the cores by nuclear Urca processes are investigated. (2) They are also used to study heating of the O-Ne-Mg core by double e-captures on 20 Ne in later stages of the evolution. Especially, the e-capture rates for a second-forbidden transition in 20 Ne are evaluated with the multipole expansion method by Walecka as well as the method of Behrens-Bühring. Possible important roles of the transition in heating the O-Ne-Mg cores and implications on the final fate of the cores (core-collapse or thermonuclear explosion) are discussed.(3) The weak rates in pf -shell nuclei are evaluated with a new Hamiltonian, GXPF1J, and applied to nucleosynthesis of iron-group elements in Type Ia supernova explosions. The over-production problem of neutron-rich iron isotopes compared with the solar abundances, which remained for the rates according to Fuller, Fowler and Newman, is much improved, and the over-production is now reduced to be within a factor of two. (4) The weak rates for nuclei with two-major shells are evaluated. For sd-pf shell in the island of inversion, the weak rates for the A=31 pair of nuclei, which are important for nuclear Urca processes in neutron-star crusts, are evaluated with the effective interaction obtained by the extended Kuo-Krenciglowa (EKK) method. Neutron-rich nuclei with and near neutron number (N ) of 50 are important for core-collapse processes in supernova explosions. The transition strengths and e-capture rates in 78 Ni are evaluated with a new shell-model Hamiltonian for the pf -sdg shell, and compared with those obtained by the randomphase-approximation (RPA) and an effective rate formula. (5) β-decay rates and half-lives of N =126 isotones, the waiting point nuclei for r-process nucleosynthesis, are evaluated by shell-model calculations with both the GT and first-forbidden transitions. The important roles of the forbidden transitions are pointed out for the isotones with larger proton number (Z). The half-lives are found to be shorter than those obtained by standard models such as the finite-range droplet model (FRDM) by Möller. (6) Neutrino-nucleus reaction cross sections on 13 C, 16 O and 40 Ar are obtained with new shell-model Hamiltonians. Implications on nucleosynthesis, neutrino detection, neutrino oscillations and neutrino mass hierarchy are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: β-Decay Rates For N =126 Isotones For R-process Nucleosynthesismentioning

confidence: 99%

Nuclear Weak Rates and Nuclear Weak Processes in Stars

Suzuki

2022

Preprint

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“…Further details on the BRIKEN detector and analysis techniques can be found in Rasco et al (2018) and Tolosa-Delgado et al (2019). We note that (as discussed in Yokoyama et al 2019), when the neutron energy distribution of the (here: lanthanide) isotopes is not known, the neutron detection efficiency-together with the statistical uncertainty-is the dominant contribution to the error of the P 1n values.…”

Section: Experimental Approachmentioning

confidence: 97%

Measuring the β-decay Properties of Neutron-rich Exotic Pm, Sm, Eu, and Gd Isotopes to Constrain the Nucleosynthesis Yields in the Rare-earth Region

Kiss

Vitéz-Sveiczer

Saito

et al. 2022

ApJ

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The β-delayed neutron-emission probabilities of 28 exotic neutron-rich isotopes of Pm, Sm, Eu, and Gd were measured for the first time at RIKEN Nishina Center using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The existing β-decay half-life (T 1/2) database was significantly increased toward more neutron-rich isotopes, and uncertainties for previously measured values were decreased. The new data not only constrain the theoretical predictions of half-lives and β-delayed neutron-emission probabilities, but also allow for probing the mechanisms of formation of the high-mass wing of the rare-earth peak located at A ≈ 160 in the r-process abundance distribution through astrophysical reaction network calculations. An uncertainty quantification of the calculated abundance patterns with the new data shows a reduction of the uncertainty in the rare-earth peak region. The newly introduced variance-based sensitivity analysis method offers valuable insight into the influence of important nuclear physics inputs on the calculated abundance patterns. The analysis has identified the half-lives of 168Sm and of several gadolinium isotopes as some of the key variables among the current experimental data to understand the remaining abundance uncertainty at A = 167–172.

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