Suchergebnisse

B. Olaizola et al. -- 6 pags., 6 figs., 2 tabs. ; The lifetime of the 03+ state in Ni66, two neutrons below the N=40 subshell gap, has been measured. The transition B(E2;03+→21+) is one of the most hindered E2 transitions in the Ni isotopic chain and it implies that, unlike Ni68, there is a spherical structure at low excitation energy. We have performed extensive shell-model calculations that correctly predict this result, obtaining a spherical 0+ state at the correct energy and with an extremely low B(E2;03+→21+) value. ; This work was partially supported by the Spanish MINECO through projects FPA2013-41267-P, FPA2014- 57196, FPA2015-65035-P, and the NuPNET network FATIMA (PRI-PIMNUP-2011-1338). The support by the European Union Seventh Framework through ENSAR (Contract No. 262010) is acknowledged. Fast timing electronics were provided by the Fast Timing Collaboration and MASTICON. B.O. acknowledges funding by the CPAN project (CSD-2007-00042@ Ingenio 2010). A.A. and S.R.L. acknowledge funding by the US National Science Foundation under Contract No. PHY-07-58100. J.A.B. acknowledges funding by the Spanish MINECO through Project FPA2012-32443. A.P. is partly funded by Programme "Centros de Excelencia Severo Ochoa" (SEV-2012-0249). ; Peer Reviewed

The low-energy structure of 65Fe has been studied by means of γ and fast-timing spectroscopy at the ISOLDE facility, CERN. A level scheme of 65Fe populated following the β-decay of 65Mn was established for the first time. It includes 41 levels and 85 transitions. The excitation energy of the β-decaying isomer in 65Fe has been precisely determined at 393.7(2) keV. The β-delayed neutron emission branch was measured as Pn = 7.9(12)%, which cannot be reconciled with the previously reported value of 21.0(5)%. Four γ rays and four excited states in 64Fe were identified as being populated following the β-n decay. Four lifetimes and five lifetime limits in the subnanosecond range have been measured using the advanced time-delayed βγγ(t) method. The level scheme is compared with shell-model calculations. Tentative spin and parity assignments are proposed based on the observed transition rates, the calculations, and the systematics of the region ; This work was supported by the Spanish MINECO (FPA2010-17142 and FPA2011-29854), CPAN (CSD-2007- 00042@ Ingenio 2010), RA-NET NuPNET (PRI-PIMNUP- 2011-1338 and PRI-PIMMNUP-2011-1361) and Comunidad de Madrid, Spain (HEPHACOS S2009/ESP-1473). Support by Grupo de Física Nuclear (GFN-UCM) and by the European Union Seventh Framework through ENSAR (Contract No. 262010) is also acknowledged. Fast timing electronics were provided by the Fast Timing Collaboration and MASTICON. B.O. acknowledges funding by the CPAN (CSD-2007- 00042@ Ingenio 2010) project. A.A. and S.R.L. acknowledge funding by the US NSF under Contract No. PHY-07-58100.

The low-energy structure of 65Fe has been studied by means of γ and fast-timing spectroscopy at the ISOLDE facility, CERN. A level scheme of 65Fe populated following the β-decay of 65Mn was established for the first time. It includes 41 levels and 85 transitions. The excitation energy of the β-decaying isomer in 65Fe has been precisely determined at 393.7(2) keV. The β-delayed neutron emission branch was measured as Pn = 7.9(12)%, which cannot be reconciled with the previously reported value of 21.0(5)%. Four γ rays and four excited states in 64Fe were identified as being populated following the β-n decay. Four lifetimes and five lifetime limits in the subnanosecond range have been measured using the advanced time-delayed βγγ(t) method. The level scheme is compared with shell-model calculations. Tentative spin and parity assignments are proposed based on the observed transition rates, the calculations, and the systematics of the region. © 2013 American Physical Society. ; This work was supported by the Spanish MINECO (FPA2010-17142 and FPA2011-29854), CPAN (CSD-2007- 00042@ Ingenio 2010), RA-NET NuPNET (PRI-PIMNUP- 2011-1338 and PRI-PIMMNUP-2011-1361) and Comunidad de Madrid, Spain (HEPHACOS S2009/ESP-1473). Support by Grupo de F´ısica Nuclear (GFN-UCM) and by the European Union Seventh Framework through ENSAR (Contract No. 262010) is also acknowledged. ; Peer Reviewed

9 pags., 8 figs., 4 tabs. ; The low-energy structure of Co65 was studied by means of γ-and fast-timing spectroscopy at the ISOLDE/CERN facility. The known level scheme of Co65 populated following the β-decay of Fe65 was expanded. The experimental results were compared with large-scale shell-model calculations. The measured long lifetime of the (1/21-) level confirms its nature as a highly collective state with proton excitations across the Z=28 gap and neutrons across the N=40 subshell. ; This work was partially supported by the Spanish MINECO through Projects No. FPA2014-57196 and No. FPA2015-65035-P and Centro de Excelencia Severo Ochoa Programme (Project No. SEV-2016-0597). Support by Grupo de Física Nuclear (GFN-UCM) and by the European Union Seventh Framework through ENSAR (Contract No. 262010) is also acknowledged. B.O. acknowledges funding by the CPAN project. S.R.L. acknowledges funding by the U.S. National Science Foundation under Contract No. PHY-07- 58100.