Suchergebnisse

4 pages, 2 figures.--PACS nrs.: 21.45.+v; 23.40.–s; 27.20.+n. ; Using beta decays of a clean source of N-13 produced at the IGISOL facility, we have measured the breakup of the C-12 (12.71 MeV) state into three alpha particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71 MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed. ; This research was supported by the Academy of Finland under the Finnish Centre of Excellence Programme 2000-2005 (Project No. 44875, Nuclear and Condensed Matter Physics Programme at JYFL), by the Spanish Agency CICYT under Contract No. AEN99-1046-C02-02, and by the European Union Fifth Framework Programme ''Improving Human Potential–Access to Research Infrastructure.'' ; Peer reviewed

5 pages, 2 tables, 3 figures.--PACS nrs.: 23.40.Hc; 27.20.+n. ; The beta decay of O-13 has been studied at the IGISOL facility of the Jyvaskyla accelerator centre (Finland). By developing a low-energy isotope-separated beam of O-13 and using a modern segmented charged-particle detector array an improved measurement of the delayed proton spectrum was possible. Protons with energy up to more than 12 MeV are measured and the corresponding log(ft) values extracted. A revised decay scheme is constructed. The connection to molecular states and the shell model is discussed. ; This work was supported by the Academy of Finland under the Finnish Centre of Excellence Programme 2000–2005 (Project No. 44875, Nuclear and Condensed Matter Physics Programme at JYFL), by the European Union Fifth Framework Programme "Improving Human Potential - Access to Research Infrastructure" contract no. HPRI-CT-1999-00044, by the Spanish CICYT Agency under Project number FPA2002-04181-C04-02, and by the EU-RI3 (Integrated Infrastructure Initiative) under contract no 506065. ; Peer reviewed