β-delayed proton emission of 69Kr and the 68Se rp-process waiting point

M. Del Santo; Z. Meisel; D. Bazin; A. Becerril; B.A. Brown; H. Crawford; R. Cyburt; S. George; G.F. Grinyer; G. Lorusso; P.F. Mantica; F. Montes; J. Pereira; H. Schatz; K. Smith; M. Wiescher

Physics Letters B (Nov 2014)

β-delayed proton emission of 69Kr and the 68Se rp-process waiting point

M. Del Santo,
Z. Meisel,
D. Bazin,
A. Becerril,
B.A. Brown,
H. Crawford,
R. Cyburt,
S. George,
G.F. Grinyer,
G. Lorusso,
P.F. Mantica,
F. Montes,
J. Pereira,
H. Schatz,
K. Smith,
M. Wiescher

Affiliations

M. Del Santo: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
Z. Meisel: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA; Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA; Corresponding author at: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA.
D. Bazin: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
A. Becerril: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA; Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
B.A. Brown: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
H. Crawford: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
R. Cyburt: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
S. George: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
G.F. Grinyer: Grand Accélérateur National d'Ions Lourds, CEA/DSM-CNRS/IN2P3, 14076 Caen, France
G. Lorusso: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA; Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
P.F. Mantica: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
F. Montes: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
J. Pereira: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
H. Schatz: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA; Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
K. Smith: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA; Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA; Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
M. Wiescher: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA; Department of Physics, University of Notre Dame, South Bend, IN 46556, USA

Journal volume & issue: Vol. 738
pp. 453 – 456

Abstract

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The slow β-decay of the 68Se waiting point in the astrophysical rp-process can in principle be bypassed by a sequential two proton capture. The rate of this reaction sequence depends exponentially on the 69Br proton separation energy. We studied β-delayed proton emission of 69Kr and extracted a proton separation energy of −641(42) keV. In addition, we determined a 69Kr β-decay half-life of T1/2=28(1) ms and an excitation energy of 3153(55) keV of the 69Kr isobaric analog state in 69Br. X-ray burst model calculations show that regardless of the values of other uncertain masses in the region, the new Sp(Br69) allows for a reaction flow via Se68(2p,γ) of at most 20%. Uncertainties are sufficiently reduced to conclude that Se68(2p,γ) has at best a very small effect on burst light curve and composition, and that 68Se is a strong rp-process waiting point. Our results also exclude the possibility of a suggested longer lived, so far unobserved, 69Br ground state. Keywords: Rp-process, Waiting point, X-ray burst

Published in Physics Letters B

ISSN: 0370-2693 (Print); 1873-2445 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Science: Physics
Website: http://www.journals.elsevier.com/physics-letters-b/

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