Precise branching ratios to unbound 12C states from 12N and 12B β-decays

• Published in: Physics letters. B Vol. 678; no. 5; pp. 459 - 464
• Main Authors: Hyldegaard, S., Forssén, C., Diget, C.Aa, Alcorta, M., Barker, F.C., Bastin, B., Borge, M.J.G., Boutami, R., Brandenburg, S., Büscher, J., Dendooven, P., Van Duppen, P., Eronen, T., Fox, S., Fulton, B.R., Fynbo, H.O.U., Huikari, J., Huyse, M., Jeppesen, H.B., Jokinen, A., Jonson, B., Jungmann, K., Kankainen, A., Kirsebom, O., Madurga, M., Moore, I., Navrátil, P., Nilsson, T., Nyman, G., Onderwater, G.J.G., Penttilä, H., Peräjärvi, K., Raabe, R., Riisager, K., Rinta-Antila, S., Rogachevskiy, A., Saastamoinen, A., Sohani, M., Tengblad, O., Traykov, E., Vary, J.P., Wang, Y., Wilhelmsen, K., Wilschut, H.W., Äystö, J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 03.08.2009; Elsevier
• Subjects: Exact sciences and technology; Nuclear physics; Physics; The physics of elementary particles and fields; 23.40.-s; 21.60.De; 27.20.+n; 21.45.-v; Perturbation theory; Shell models; Branching ratio; Nucleons; Beta decay; Alpha particles
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2009.06.064

Two complementary experimental techniques have been used to extract precise branching ratios to unbound states in 12C from 12N and 12B β-decays. In the first the three α-particles emitted after β-decay are measured in coincidence in separate detectors, while in the second method 12N and 12B are implanted in a detector and the summed energy of the three α-particles is measured directly. For the narrow states at 7.654 MeV (0+) and 12.71 MeV (1+) the resulting branching ratios are both smaller than previous measurements by a factor of ≃2. The experimental results are compared to no-core shell model calculations with realistic interactions from chiral perturbation theory, and inclusion of three-nucleon forces is found to give improved agreement.