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HK: Fachverband Physik der Hadronen und Kerne

HK 15: Kernphysik / Spektroskopie

HK 15.5: Talk

Monday, March 10, 2008, 17:45–18:00, 2G

First identification of shape coexistence in ³⁰Mg via electron spectroscopy — •W. Schwerdtfeger^1,3, V. Bildstein^2,3, L. Fraile⁴, R. Gernhäuser^2,3, D. Habs^1,3, R. Hertenberger^1,3, P. Hoff⁵, U. Köster⁶, Th. Kröll^2,3, R. Krücken^2,3, R. Lutter^1,3, H. Mach⁷, P. Ring^1,3, P.G. Thirolf^1,3, and K. Wimmer^1,3 for the IS414 collaboration — ¹Department of Physics, LMU München — ²E12, TU München — ³Maier-Leibnitz-Laboratorium, Garching — ⁴CERN, Geneva — ⁵Department of Chemistry, University of Oslo — ⁶ILL, Grenoble — ⁷Department of Radiation Sciences, Uppsala University

The 1789 keV level in ³⁰Mg was unambiguously identified as the second excited 0⁺ state by measuring its E0 transition to the ground state via conversion electron spectroscopy. This level corresponds to the strongly deformed intruder 0₂⁺ state, thus proving for the first time shape coexistence in this nucleus at the borderline of the ’Island of Inversion’ around N ≈ 20. The matrix element ρ²(E0,0₂⁺ → 0₁⁺) = 3.6(7) · 10⁻³ allows to deduce the squared mixing amplitude a² between the unperturbed lowest two 0⁺ states, indicating a rather weak coupling between the spherical and deformed configurations. The measurement was performed following the β decay of ³⁰Na at the ISOLDE facility. ^*Supported by BMBF under contract 06 ML 234.