Stellar weak-interaction rates for sd-shell nuclei. I - Nuclear matrix element systematics with application to Al-26 and selected nuclei of importance to the supernova problem

TLDR

The study calculates astrophysical positron emission, continuum electron capture, and neutrino energy loss rates for 26Al→26Mg and other sd‑shell nuclei relevant to supernova evolution. The authors use measured nuclear level data and shell‑model based estimates for unmeasured matrix elements, assigning uncertainties and providing average Gamow‑Teller values for other sd‑shell nuclei. The experimentally determined matrix elements dominate the rates across most conditions, and the calculated rates agree broadly with Hansen’s but show significant differences at temperatures and densities critical for 26Al production and late presupernova neutronization and neutrino loss. Published in The Astrophysical Journal Supplement Series (March 1980), DOI 10.1086/190657.

Abstract

view Abstract Citations (399) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Stellar weak-interaction rates for sd-shell nuclei. I - Nuclear matrix element systematics with application to Al-26 and selected nuclei of importance to the supernova problem Fuller, G. M. ; Fowler, W. A. ; Newman, M. J. Abstract Astrophysical positron emission, continuum electron capture, and neutrino energy loss rates are calculated for 26Al → 26Mg, 30P → 30Si;, 31S → 31P, 32S → 32P 33S → 33P, and 35Cl → 35S. Measured nuclear level information and matrix elements are used where available. Unmeasured matrix elements for allowed transitions are assigned on the basis of simple shell model arguments and the results of detailed large-scale shell model calculations by Wildenthal and his collaborators. The experimentally determined matrix elements are found to dominate the rates over most of the range of temperatures and densities considered. The uncertainties in the rates are estimated. Appropriate average matrix elements for unmeasured Gamow-Teller transitions are estimated for use in other sd-shell nuclei. The rates presented agree roughly with those of Hansen over a wide range of conditions, but potentially important differences in the rates exist at temperatures and densities relevant for the production and destruction of 26Al and for neutronization and neutrino loss in the late stages of presupernova evolution. Publication: The Astrophysical Journal Supplement Series Pub Date: March 1980 DOI: 10.1086/190657 Bibcode: 1980ApJS...42..447F Keywords: Neutrinos; Nuclear Astrophysics; Nuclear Reactions; Supernovae; Weak Interactions (Field Theory); Aluminum 26; Electron Capture; Electron Transitions; Energy Dissipation; Positrons; Reaction Kinetics; Astrophysics full text sources ADS |