Stuttgart 2012 – scientific programme

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MS: Fachverband Massenspektrometrie

MS 5: Precision Mass Spectrometry and Fundamental Applications II

MS 5.2: Talk

Tuesday, March 13, 2012, 14:30–14:45, V57.06

Direct mass measurements above Z = 100 — •E. Minaya Ramirez¹, D. Ackermann², K. Blaum^3,4, M. Block², C. Droese⁵, Ch.E. Düllmann^1,2,6, M. Dworschak², M. Eibach⁶, S. Eliseev³, E. Haettner^2,7, F. Herfurth², F.P. Heßberger², S. Hofmann², J. Ketelaer³, J. Ketter³, G. Marx⁵, M. Mazzocco⁸, D. Nesterenko⁹, Yu. Novikov⁹, W.R. Plass^2,7, S. Rahaman¹⁰, D. Rodríguez¹¹, C. Scheidenberger^2,7, L. Schweikhard⁵, P.G. Thirolf¹², G.K. Vorobjev^2,9, and C. Weber¹² — ¹Helmholtz-Institut Mainz — ²GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt — ³Max-Planck-Institut für Kernphysik, Heidelberg — ⁴Ruprecht-Karls-Universität Heidelberg — ⁵Ernst-Moritz-Arndt-Universität, Greifswald — ⁶Johannes Gutenberg-Universität Mainz — ⁷Justus-Liebig-Universität Gießen — ⁸Dipartimento di Fisica and INFN Sezione di Padova — ⁹PNPI RAS Gatchina, St. Petersburg — ¹⁰LANL, Los Alamos — ¹¹Universidad de Granada — ¹²Ludwig-Maximilians-Universität München

High-precision mass measurements of radionuclides are a direct way to obtain the nuclear binding energy, a crucial parameter to investigate the nuclear shell structure. Furthermore, the combination of α-decay spectroscopy and directly measured masses above fermium (Z > 100) allows determining the masses of higher-Z nuclides to support the search for the island of stability of superheavy elements. Besides, mass measurements of the heaviest actinides allow studying the deformed shell gap N = 152 connected to the spherical shell gap in much heavier nuclei by the same single-particle orbitals. Recently, the masses of the nuclides ²⁵⁵No and ^255,256Lr have been measured with high accuracy using the Penning trap mass spectrometer SHIPTRAP at GSI Darmstadt. In addition, the accuracy of the ²⁵²No and ²⁵⁴No masses (previously measured at SHIPTRAP) was further improved. The radionuclides were produced in fusion-evaporation reactions and separated from the primary beam by the velocity filter SHIP. Until now the masses of the lawrencium isotopes were only estimated from systematic trends and the extension to ²⁵⁶Lr represents a new stage in mass measurements of elements with very low cross sections performed with a Penning trap. Work supported in part by BMBF (06ML9148).