The 76Se Gamow–Teller strength distribution and its importance for stellar electron capture rates

Zhi, Qi‐Jun; Langanke, K.; Martı́nez-Pinedo, G.; Nowacki, F.; Sieja, K.

doi:10.1016/j.nuclphysa.2011.04.010

Cited by 38 publications

(65 citation statements)

References 34 publications

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“…However, it has been shown in [43] that nuclear correlations induced by the residual interaction move nucleons across the shell gap enabling GT + transitions and making electron capture on nuclei the dominating weak interaction process during collapse [43,44]. We add two remarks: The unblocking of the GT + strength across the N = 40 shell closure has been experimentally confirmed for 76 Se (with 34 protons and 42 neutrons) [45], in agreement with shell model studies [46]. Supplemented by transfer reaction experiments [47] the shell model study shows that the neutron occupation numbers in the g 9/2 orbital is about 6 (rather than 2 as in the IPM).…”

Section: Electron Captures In Supernovaesupporting

confidence: 78%

“…Supplemented by transfer reaction experiments [47] the shell model study shows that the neutron occupation numbers in the g 9/2 orbital is about 6 (rather than 2 as in the IPM). Furthermore, shell model studies clearly show that the description of cross-shell correlations is a rather slowly converging process requiring the consideration of multi particle-multi hole configurations [48,49,46]. The diagonalization shell model electron capture rates agree reasonably well with those obtained by the SMMC+RPA approach at such astrophysical conditions at which nuclei with Z < 40, N > 40 dominate.…”

Section: Electron Captures In Supernovaementioning

confidence: 54%

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Weak-interaction processes in core-collapse supernovae

Langanke¹

2015

AIP Conference Proceedings

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Abstract. Weak interaction processes play an important role for the dynamics of a core-collapse supernova. Due to progress of nuclear modeling and constrained by data it has been possible to improve the rates of these processes for supernova conditions decisively. This manuscript describes the recent advances and the current status in deriving electron capture rates on nuclei and of inelastic neutrino-nucleus scattering for applications in supernova simulations and briefly discusses their impact on such studies.

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Section: Electron Captures In Supernovaesupporting

confidence: 78%

Section: Electron Captures In Supernovaementioning

confidence: 54%

Weak-interaction processes in core-collapse supernovae

Langanke¹

2015

AIP Conference Proceedings

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“…Experimentally this is observed for 76 Se (Z = 34, N = 42) which has a non-vanishing GT + strength distribution (required for the double-beta decay of 76 Ge [12,21]), made possible by a sizable neutronhole structure in the pf shell as determined from transfer reactions [22]. The experimental GT + distribution is well described by shell model diagonalization studies [23] confirming that cross-shell correlations require multiparticle-multi-hole correlations [24,25]. For stellar electron capture rates, these correlations have been consid-ered within a hybrid model, in which nuclear partial occupation numbers have been calculated within the Shell Model Monte Carlo Approach [26,27] which allows to determine thermally-averaged nuclear properties at finite temperatures considering correlations in unprecedentedly large model spaces (here the full pf − gds shells).…”

Section: Introductionmentioning

confidence: 82%

Unblocking of stellar electron capture for neutron-rich N=50 nuclei at finite temperature

Dzhioev¹,

Langanke

Martı́nez-Pinedo

et al. 2020

Phys. Rev. C

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We have calculated electron capture rates for neutron-rich N = 50 nuclei ( 78 Ni, 82 Ge, 86 Kr, 88 Sr) within the Thermal QRPA approach at temperatures T = 0, corresponding to capture on the ground-state, and at T = 10 GK (0.86 MeV), which is a typical temperature at which the N = 50 nuclei are abundant during a supernova collapse. In agreement with recent experiments, we find no Gamow-Teller (GT+) strength at low excitation energies, E < 7 MeV, caused by Pauli blocking induced by the N = 50 shell gap. At the astrophysically relevant temperatures this Pauli blocking of the GT+ strength is overcome by thermal excitations across the Z = 40 proton and N = 50 neutron shell gaps, leading to a sizable GT contribution to the electron capture. At the high densities, at which the N = 50 nuclei are important for stellar electron capture, forbidden transitions contribute noticeably to the capture rate. Our results indicate that the neutron-rich N = 50 nuclei do not serve as an obstacle of electron capture during the supernova collapse. PACS numbers: 26.50.+x, 23.40.-s 21.60.Jz, 24.10.Pa,

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“…Being based on fits of pf -shell nuclei, the approximation proposed in Ref. [15] might not be appropriate for EC rates of heavy nuclei, which, due to cross-shell correlations, manifest suppression of Pauli blocking effects [66]. This unblocking of the GT transition was predicted by theoretical models for nuclei with Z < 40 and N > 40, and confirmed by experiments.…”

Section: Electron Capture Ratesmentioning

confidence: 97%

Impact of electron capture rates for nuclei far from stability on core-collapse supernovae

et al. 2020

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The impact of electron-capture (EC) cross sections on neutron-rich nuclei on the dynamics of corecollapse during infall and early post-bounce is studied performing spherically symmetric simulations in general relativity using a multigroup scheme for neutrino transport and full nuclear distributions in extended nuclear statistical equilibrium models. We thereby vary the prescription for EC rates on individual nuclei, the nuclear interaction for the EoS, the mass model for the nuclear statistical equilibrium distribution and the progenitor model. In agreement with previous works, we show that the individual EC rates are the most important source of uncertainty in the simulations, while the other inputs only marginally influence the results. A recently proposed analytic formula to extrapolate microscopic results on stable nuclei for EC rates to the high densities and temperatures and the neutron rich region, with a functional form motivated by nuclear-structure data and parameters fitted from large scale shell model calculations, is shown to lead to a sizable (16%) reduction of the electron fraction at bounce compared to more primitive prescriptions for the rates, leading to smaller inner core masses and slower shock propagation. We show that the EC process involves ≈ 130 different nuclear species around 86 Kr mainly in the N = 50 shell closure region, and establish a list of the most important nuclei to be studied in order to constrain the global rates.

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The 76Se Gamow–Teller strength distribution and its importance for stellar electron capture rates

Cited by 38 publications

References 34 publications

Weak-interaction processes in core-collapse supernovae

Weak-interaction processes in core-collapse supernovae

Unblocking of stellar electron capture for neutron-rich N=50 nuclei at finite temperature

Impact of electron capture rates for nuclei far from stability on core-collapse supernovae

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