1. β+Gamow-Teller Transition Strengths fromTi46and Stellar Electron-Capture Rates
- Author
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Alexandra Gade, G. Perdikakis, Shumpei Noji, Zach Meisel, E. Lunderberg, C. Sullivan, S. J. Williams, C. J. Guess, R. G. T. Zegers, C. Langer, C. M. Campbell, A. L. Cole, C. Walz, G. W. Hitt, M. Scott, H. J. Doster, B. A. Brown, D. Weisshaar, Sam M. Austin, T.R. Baugher, S. Gupta, Kathrin Wimmer, S. Lipschutz, J. Pereira, S. R. Stroberg, L. Valdez, F. Recchia, D. Bazin, R. Meharchand, and Hendrik Schatz
- Subjects
Physics ,Nuclear physics ,Reaction rate ,Electron capture ,Double beta decay ,Nuclear Theory ,Quasiparticle ,General Physics and Astronomy ,Nuclear Experiment ,Space (mathematics) ,Random phase approximation ,Measure (mathematics) ,Stellar evolution - Abstract
The Gamow-Teller strength in the β(+) direction to (46)Sc was extracted via the (46)Ti(t,(3)He + γ) reaction at 115 MeV/u. The γ-ray coincidences served to precisely measure the very weak Gamow-Teller transition to a final state at 991 keV. Although this transition is weak, it is crucial for accurately estimating electron-capture rates in astrophysical scenarios with relatively low stellar densities and temperatures, such as presupernova stellar evolution. Shell-model calculations with different effective interactions in the pf shell-model space do not reproduce the experimental Gamow-Teller strengths, which is likely due to sd-shell admixtures. Calculations in the quasiparticle random phase approximation that are often used in astrophysical simulations also fail to reproduce the experimental Gamow-Teller strength distribution, leading to strongly overestimated electron-capture rates. Because reliable theoretical predictions of Gamow-Teller strengths are important for providing astrophysical electron-capture reaction rates for a broad set of nuclei in the lower pf shell, we conclude that further theoretical improvements are required to match astrophysical needs.
- Published
- 2014