Observation of gamma-delayed 3 alpha breakup of the 15.11 and 12.71 MeV states in C-12
Journal article, 2009

The reactions B-10(He-3, p alpha alpha alpha) at 4.9 MeV and B-11(He-3, d alpha alpha alpha) at 8.5 MeV have been used to investigate the gamma decay of states in C-12. By measuring the four-body final state in complete kinematics we are able to detect gamma transitions indirectly. We find gamma transitions from the 15.11 MeV state in C-12 to the 12.71, 11.83, 10.3 and 7.65 MeV states followed by their breakup into three alpha particles. The relative gamma-ray branching ratios obtained are (1.2 +/- 0.3), (0.32 +/- 0.12), (1.4 +/- 0.2) and (4.4 +/- 0.8)%, respectively, with the remaining (92.7 +/- 1.0)% of the gamma decays going to the bound states. We obtain Gamma(alpha)/Gamma = (2.8 +/- 1.2)% for the isospinforbidden alpha decay of the 15.11 MeV state. From the 12.71 MeV state we find gamma transitions to the 10.3 and 7.65 MeV states. The relative gamma-ray branching ratios are (0.9(-0.5)(+0.6)) and (2.6(-1.2)(+1.6))%, respectively, with the remaining (96.6(-1.3)(+1.7))% of the gamma decays going to the bound states. Finally. we discuss the relation between the beta decay of N-12 and B-12 to states in C-12 and the gamma decay of the 15.11 MeV analog in C-12 to the same states. (C) 2009 Elsevier B.V. All rights reserved.

decay

deduced gamma transition

unbound state

electron-scattering

light-nuclei

transitions

isovector

complete kinematics

Author

O. S. Kirsebom

Aarhus University

M. Alcorta

Spanish National Research Council (CSIC)

M. J. G. Borge

Spanish National Research Council (CSIC)

M. Cubero

Spanish National Research Council (CSIC)

C. A. Diget

University of York

R. Dominguez-Reyes

Spanish National Research Council (CSIC)

L. Fraile

Spanish National Research Council (CSIC)

B. R. Fulton

University of York

H. O. U. Fynbo

Aarhus University

D. Galaviz

Spanish National Research Council (CSIC)

G. Garcia

Universidad Autonoma de Madrid (UAM)

S. Hyldegaard

Aarhus University

H. B. Jeppesen

Aarhus University

Björn Jonson

Chalmers, Applied Physics, Subatomic Physics

P. Joshi

University of York

M. Madurga

Spanish National Research Council (CSIC)

A. Maria

Spanish National Research Council (CSIC)

A. Munoz

Universidad Autonoma de Madrid (UAM)

Thomas Nilsson

Chalmers, Applied Physics, Subatomic Physics

Göran Hugo Nyman

Chalmers, Applied Physics, Subatomic Physics

D. Obradors

Spanish National Research Council (CSIC)

A. Perea

Spanish National Research Council (CSIC)

K. Riisager

Aarhus University

Olof Tengblad

Spanish National Research Council (CSIC)

M. Turrion

Spanish National Research Council (CSIC)

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

0370-2693 (ISSN)

Vol. 680 1 44-49

Subject Categories (SSIF 2011)

Subatomic Physics

DOI

10.1016/j.physletb.2009.08.034

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