Exploiting Isospin Symmetry to Study the Role of Isomers in Stellar Environments

S. Hallam, G. Lotay, A. Gade, D. T. Doherty, J. Belarge, P. C. Bender, B. A. Brown, J. Browne, W. N. Catford, B. Elman, A. Estradé, M. R. Hall, B. Longfellow, E. Lunderberg, F. Montes, M. Moukaddam, P. O’Malley, W.-J. Ong, H. Schatz, D. Seweryniak, K. Schmidt, N. K. Timofeyuk, D. Weisshaar, and R. G. T. Zegers

Phys. Rev. Lett. 126, 042701 – Published 29 January 2021

Abstract

Proton capture on the excited isomeric state of ${}^{26}{Al}$ strongly influences the abundance of ${}^{26}{Mg}$ ejected in explosive astronomical events and, as such, plays a critical role in determining the initial content of radiogenic ${}^{26}{Al}$ in presolar grains. This reaction also affects the temperature range for thermal equilibrium between the ground and isomeric levels. We present a novel technique, which exploits the isospin symmetry of the nuclear force, to address the long-standing challenge of determining proton-capture rates on excited nuclear levels. Such a technique has in-built tests that strongly support its veracity and, for the first time, we have experimentally constrained the strengths of resonances that dominate the astrophysical ${}^{26 m}{Al} (p, γ) {}^{27}{Si}$ reaction. These constraints demonstrate that the rate is at least a factor $\sim 8$ lower than previously expected, indicating an increase in the stellar production of ${}^{26}{Mg}$ and a possible need to reinvestigate sensitivity studies involving the thermal equilibration of ${}^{26}{Al}$ .

Received 23 October 2020
Revised 23 November 2020
Accepted 12 January 2021

DOI:https://doi.org/10.1103/PhysRevLett.126.042701

Physics Subject Headings (PhySH)

Nuclear astrophysics Nuclear structure & decays Transfer reactions

Nuclear Physics

Authors & Affiliations

S. Hallam¹, G. Lotay¹, A. Gade ^2,3,4, D. T. Doherty¹, J. Belarge², P. C. Bender^2,*, B. A. Brown^2,3,4, J. Browne^2,3,4, W. N. Catford¹, B. Elman^2,3, A. Estradé⁵, M. R. Hall⁶, B. Longfellow^2,3, E. Lunderberg^2,3, F. Montes^2,4, M. Moukaddam^1,†, P. O’Malley⁶, W.-J. Ong^2,3, H. Schatz^2,3,4, D. Seweryniak⁷, K. Schmidt ^2,4,‡, N. K. Timofeyuk ¹, D. Weisshaar ², and R. G. T. Zegers^2,3,4

¹Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
²National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
³Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
⁴Joint Institute for Nuclear Astrophysics, Center for the Evolution of the Elements, Michigan State University, East Lansing, Michigan 48824, USA
⁵Department of Physics, Central Michigan University, Mount Pleasant, Michigan 48859, USA
⁶Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
⁷Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

^*Present address: Department of Physics, University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA.
^†Present address: Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France.
^‡Present address: Institute of Radiation Physics, Helmholts-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.