Sep 23, 2019
Experimental constraint on stellar electron-capture rates from the Sr 88 (t, He 3 +γ) Rb 88 reaction at 115 MeV/u
Physical Review C
- Volume
- 100
- Number
- 3
- Language
- Publishing type
- Research paper (scientific journal)
- DOI
- 10.1103/PhysRevC.100.032801
The Gamow-Teller strength distribution from Sr88 was extracted from a (t,He3+γ) experiment at 115MeV/u to constrain estimates for the electron-capture rates on nuclei around N=50, between and including Ni78 and Sr88, which are important for the late evolution of core-collapse supernovae. The observed Gamow-Teller strength below an excitation energy of 8 MeV was consistent with zero and below 10 MeV amounted to 0.1±0.05. Except for a very-weak transition that could come from the 2.231-MeV 1+ state, no γ lines that could be associated with the decay of known 1+ states were identified. The derived electron-capture rate from the measured strength distribution is more than an order of magnitude smaller than rates based on the single-state approximation presently used in astrophysical simulations for most nuclei near N=50. Rates based on shell-model and quasiparticle random-phase approximation calculations that account for Pauli-blocking and core-polarization effects provide better estimates than the single-state approximation, although a relatively strong transition to the first 1+ state in Rb88 is not observed in the data. Pauli-unblocking effects due to high stellar temperatures could partially counter the low electron-capture rates. The new data serve as a zero-temperature benchmark for constraining models used to estimate such effects.
- Link information
- ID information
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- DOI : 10.1103/PhysRevC.100.032801
- ISSN : 2469-9985
- eISSN : 2469-9993
- SCOPUS ID : 85072984236