Evidence for the existence of the astrophysically important 6.40-MeV state of ${}^{31}$S

Evidence for the existence of the astrophysically important 6.40-MeV state of $^{31}$ S

D. Irvine, A. A. Chen, A. Parikh, K. Setoodehnia, T. Faestermann, R. Hertenberger, H.-F. Wirth, V. Bildstein, S. Bishop, J. A. Clark, C. M. Deibel, J. Hendriks, C. Herlitzius, R. Krücken, W. N. Lennard, O. Lepyoshkina, R. Longland, G. Rugel, D. Seiler, K. Straub, and C. Wrede

Phys. Rev. C 88, 055803 – Published 27 November 2013

Abstract

Proton-unbound excited states of $^{31}$ S have been populated with the $^{32}$ S( $d, t$ ) $^{31}$ S reaction at a beam energy of 24 MeV. Tritons corresponding to $^{31}$ S states with $E_{x} (^{31} S) \approx 6.3$ – $7.1$ MeV were momentum analyzed with a high resolution quadrupole-dipole-dipole-dipole (Q3D) magnetic spectrograph at six angles ranging from $θ_{lab} = 15^{\circ}$ to $58 . 5^{\circ}$ . We report a statistically significant detection of an astrophysically important state at $E_{x} (^{31} S) = 6402$ (2) keV, whose existence as a third state in this region has been under debate. Using updated $A = 31$ nuclear structure information, we present a new set of proposed $^{31}$ S- $^{31}$ P mirror assignments for $^{31}$ S, in which this state is tentatively assigned a spin of 7/2. This level, corresponding to a $^{30}$ P + $p$ resonance at 271 keV, is likely to have a significant influence on the $^{30}$ P( $p, γ$ ) $^{31}$ S reaction rate in explosive hydrogen burning in classical novae.

Received 25 July 2013

DOI:https://doi.org/10.1103/PhysRevC.88.055803

Authors & Affiliations

D. Irvine^1,*, A. A. Chen¹, A. Parikh^2,3, K. Setoodehnia¹, T. Faestermann³, R. Hertenberger⁴, H.-F. Wirth⁴, V. Bildstein⁵, S. Bishop³, J. A. Clark⁶, C. M. Deibel^6,7,8, J. Hendriks⁹, C. Herlitzius³, R. Krücken^3,10, W. N. Lennard⁹, O. Lepyoshkina³, R. Longland², G. Rugel³, D. Seiler³, K. Straub³, and C. Wrede^11,12

¹Department of Physics & Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
²Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, E-08036 Barcelona, Spain
³Physik Department E12, Technische Universität München, D-85748 Garching, Germany
⁴Fakultät für Physik, Ludwig-Maximilians-Universität München, D-85784 Garching, Germany
⁵Department of Physics, University of Guelph, Guelph, Ontario N1G 2M7, Canada
⁶Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
⁷Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, Michigan 48824, USA
⁸Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803-4001, USA
⁹Department of Physics & Astronomy, Western University, London, Ontario N6A 3K7, Canada
¹⁰Science Division, TRIUMF National Laboratory, Vancouver, British Columbia V6T 2A3, Canada
¹¹Department of Physics, University of Washington, Seattle, Washington 98195, USA
¹²Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA

^*irvinedt@mcmaster.ca

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Vol. 88, Iss. 5 — November 2013

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Physical Review C

covering nuclear physics