Observation of gamma-delayed 3 alpha breakup of the 15.11 and 12.71 MeV states in C-12
Artikel i vetenskaplig tidskrift, 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

Författare

O. S. Kirsebom

Aarhus Universitet

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 Universitet

D. Galaviz

CSIC - Instituto de Estructura de la Materia (IEM)

G. Garcia

Universidad Autonoma de Madrid (UAM)

S. Hyldegaard

Aarhus Universitet

H. B. Jeppesen

Aarhus Universitet

Björn Jonson

Chalmers, Teknisk fysik, Subatomär fysik

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, Teknisk fysik, Subatomär fysik

Göran Hugo Nyman

Chalmers, Teknisk fysik, Subatomär fysik

D. Obradors

CSIC - Instituto de Estructura de la Materia (IEM)

A. Perea

CSIC - Instituto de Estructura de la Materia (IEM)

K. Riisager

Aarhus Universitet

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 44-49

Ämneskategorier

Subatomär fysik

DOI

10.1016/j.physletb.2009.08.034