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

O. S. Kirsebom ; M. Alcorta ; M. J. G. Borge ; M. Cubero ; C. A. Diget ; R. Dominguez-Reyes ; L. Fraile ; B. R. Fulton ; H. O. U. Fynbo ; D. Galaviz ; G. Garcia ; S. Hyldegaard ; H. B. Jeppesen ; Björn Jonson (Institutionen för fundamental fysik, Subatomär fysik) ; P. Joshi ; M. Madurga ; A. Maira ; A. Munoz ; Thomas Nilsson (Institutionen för fundamental fysik, Subatomär fysik) ; Göran Nyman (Institutionen för fundamental fysik, Subatomär fysik) ; D. Obradors ; A. Perea ; K. Riisager ; Olof Tengblad ; M. Turrion
Physics Letters B (0370-2693). Vol. 680 (2009), 1, p. 44-49.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: complete kinematics, unbound state, deduced gamma transition, electron-scattering, light-nuclei, isovector, transitions, decay



Denna post skapades 2009-12-11. Senast ändrad 2014-09-02.
CPL Pubid: 103395

 

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Institutioner (Chalmers)

Institutionen för fundamental fysik, Subatomär fysik (2005-2013)

Ämnesområden

Kärnfysik
Lågenergifysik

Chalmers infrastruktur