Heidelberg 2015 – scientific programme
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MS: Fachverband Massenspektrometrie
MS 1: Precision Mass Spectrometry 1
MS 1.3: Talk
Monday, March 23, 2015, 12:15–12:30, PH/HS2
Probing the N=32 shell closure below the magic proton number Z=20: Mass measurements of the exotic isotopes 52,53K — •M. Rosenbusch1, P. Ascher2, D. Atanasov2, C. Barbieri3, D. Beck4, K. Blaum2, Ch. Borgmann2, M. Breitenfeldt5, R. B. Cakirli2,6, S. George2, F. Herfurth4, M. Kowalska7, S. Kreim2,7, D. Lunney8, V. Manea8, P. Navrátil9, D. Neidherr4, L. Schweikhard1, V. Somà10,11,12, J. Stanja13, F. Wienholtz1, N. R. Wolf1,2, and K. Zuber13 — 1Institut für Physik, Ernst-Moritz-Arndt-Universität, 17487 Greifswald — 2Max-Planck-Institut für Kernphysik, 69117 Heidelberg — 3Department of Physics, University of Surrey, Guildford GU2 7XH, UK — 4GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt — 5Katholieke Universiteit, 3000 Leuven, Belgium — 6University of Istanbul, 334452 Istanbul, Turkey — 7CERN, CH-1211 Geneva, Switzerland — 8CSNSM-IN2P3-CNRS, Université Paris-Sud, 91406 Orsay, France — 9TRIUMF, V6T 2A3 Vancouver, BC, Canada — 10ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt — 11Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany — 12CEA-Saclay, IRFU/Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France — 13Institut für Kern- und Teilchenphysik, Technische Universität Dresden, 01069 Dresden
The Penning-trap mass spectrometer ISOLTRAP at the on-line isotope separator ISOLDE/CERN has been set up for precision mass measurements of short-lived nuclides and has been continuously improved for accessing more exotic species. A crucial step forward has been made with the installation of a multi-reflection time-of-flight mass separator/spectrometer (MR-ToF MS), which enables fast mass separation and a direct mass determination of the involved species. With new mass measurements of the exotic isotopes 52,53K, the recent investigations of the neutron-shell closure at N = 32 for calcium [1] could be extended for an element below the magic proton number Z = 20 for the first time. The resulting two-neutron separation energies reveal a 3 MeV shell gap at N = 32, which is slightly lower than for 52Ca, highlighting the doubly-magic nature of this nuclide. While Hartree-Fock-Boguliubov calculations have difficulties to reproduce these findings, fully ab initio calculations in the framework of Gorkov-Green function theory performed for the first time beyond N = 32 agree with the measured shell effect.
[1] F. Wienholtz et al., Nature 498, 346-349 (2013)