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.
transitions
isovector
unbound state
complete kinematics
electron-scattering
deduced gamma transition
decay
light-nuclei
Author
O. S. Kirsebom
Aarhus University
M. Alcorta
CSIC - Instituto de Estructura de la Materia (IEM)
M. J. G. Borge
CSIC - Instituto de Estructura de la Materia (IEM)
M. Cubero
CSIC - Instituto de Estructura de la Materia (IEM)
C. A. Diget
University of York
R. Dominguez-Reyes
CSIC - Instituto de Estructura de la Materia (IEM)
L. Fraile
CSIC - Instituto de Estructura de la Materia (IEM)
B. R. Fulton
University of York
H. O. U. Fynbo
Aarhus University
D. Galaviz
CSIC - Instituto de Estructura de la Materia (IEM)
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
CSIC - Instituto de Estructura de la Materia (IEM)
A. Maria
CSIC - Instituto de Estructura de la Materia (IEM)
A. Munoz
Universidad Autonoma de Madrid (UAM)
Thomas Nilsson
Chalmers, Applied Physics, Subatomic Physics
Göran Hugo Nyman
Chalmers, Applied Physics, Subatomic Physics
D. Obradors
CSIC - Instituto de Estructura de la Materia (IEM)
A. Perea
CSIC - Instituto de Estructura de la Materia (IEM)
K. Riisager
Aarhus University
Olof Tengblad
CSIC - Instituto de Estructura de la Materia (IEM)
M. Turrion
CSIC - Instituto de Estructura de la Materia (IEM)
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
0370-2693 (ISSN)
Vol. 680 1 44-49Subject Categories
Subatomic Physics
DOI
10.1016/j.physletb.2009.08.034