Advanced search
Start date
Betweenand
(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Constraints for stellar electron-capture rates on Kr-86 via the Kr-86(t, He-3 + gamma)Br-86 reaction and the implications for core-collapse supernovae

Full text
Author(s):
Show less -
Titus, E. R. [1, 2, 3] ; Ney, E. M. [4] ; Zegers, R. G. T. [1, 2, 3] ; Bazin, D. [1, 2] ; Belarge, J. [2] ; Bender, P. C. [5] ; Brown, B. A. [1, 2, 3] ; Campbell, C. M. [6] ; Elman, B. [1, 2] ; Engel, J. [4] ; Gade, A. [1, 2, 3] ; Gao, B. [7] ; Kwan, E. [2] ; Lipschutz, S. [1, 2, 3] ; Longfellow, B. [1, 2] ; Lunderberg, E. [1, 2] ; Mijatovic, T. [2] ; Noji, S. [2, 3] ; Pereira, J. [2, 3] ; Schmitt, J. [1, 2, 3] ; Sullivan, C. [1, 2, 3] ; Weisshaar, D. [2] ; Zamora, J. C. [8]
Total Authors: 23
Affiliation:
[1] Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 - USA
[2] Michigan State Univ, Natl Superconducting Cyclotron Lab, E Lansing, MI 48824 - USA
[3] Michigan State Univ, Joint Inst Nucl Astrophys, Ctr Evolut Elements, E Lansing, MI 48824 - USA
[4] Univ North Carolina Chapel Hill, Dept Phys & Astron, Chapel Hill, NC 27599 - USA
[5] Univ Massachusetts, Dept Phys, Lowell, MA 01854 - USA
[6] Lawrence Berkeley Natl Lab, Berkeley, CA 94720 - USA
[7] Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Gansu - Peoples R China
[8] Univ Sao Paulo, Inst Fis, BR-05508090 Sao Paulo - Brazil
Total Affiliations: 8
Document type: Journal article
Source: Physical Review C; v. 100, n. 4 OCT 22 2019.
Web of Science Citations: 2
Abstract

Background: In the late stages of stellar core collapse just prior to core bounce, electron captures on medium-heavy nuclei drive deleptonization. Therefore, simulations require the use of accurate reaction rates. Nuclei with neutron number near N = 50 above atomic number Z = 28 play an important role. Rates presently used in astrophysical simulations rely primarily on a relatively simple single-state approximation. In order to improve the accuracy of the astrophysical simulations, experimental data are needed to test the electron-capture rates and to guide the development of better theoretical models and astrophysical simulations. Purpose: The purpose of the present work was to measure the Gamow-Teller transition strength from Kr-86 to Br-86, to derive the stellar electron-capture rates based on the extracted strengths, and to compare the derived rates with rates based on shell-model and quasiparticle random-phase approximation (QRPA) Gamow-Teller strengths calculations, as well as the single-state approximation. An additional purpose was to test the impact of using improved electron-capture rates on the late evolution of core-collapse supernovae. Method: The Gamow-Teller strengths from Kr-86 were extracted from the Kr-86(t, He-3 + gamma) charge-exchange reaction at 115MeV/u. The electron-capture rates were calculated as a function of stellar density and temperature. Besides the case of Kr-86, the electron-capture rates based on the QRPA calculations were calculated for 78 additional isotopes near N = 50 above Z = 28. The impact of using these rates instead of those based on the single-state approximation is studied in a spherically symmetrical simulation of core collapse just prior to bounce. Results: The derived electron-capture rates on Kr-86 from the experimental Gamow-Teller strength distribution are much smaller than the rates estimated based on the single-state approximation. Rates based on Gamow-Teller strengths estimated in shell-model and QRPA calculations are more accurate. The core-collapse supernova simulation with electron-capture rates based on the QRPA calculations indicate a significant reduction in the deleptonization during the collapse phase. Conclusions: It is important to utilize microscopic theoretical models that are tested by experimental data to constrain and estimate Gamow-Teller strengths and derived electron-capture rates for nuclei near N = 50 that are inputs for astrophysical simulations of core-collapse supernovae and their multimessenger signals, such as the emission of neutrinos and gravitational waves. (AU)

FAPESP's process: 18/04965-4 - Study of structure and nuclear reactions induced by exotic nuclei using active targets
Grantee:Juan Carlos Zamora Cardona
Support type: Scholarships in Brazil - Post-Doctorate