Heidelberg 2015 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 45: Structure and Dynamics of Nuclei 9

HK 45.5: Vortrag

Mittwoch, 25. März 2015, 16:00–16:15, T/HS2

Deformation of ground and beta-bands: search for the 2_β⁺ → 0_β⁺ decay in ¹⁵⁸Gd — •J. Stamm¹, V. Werner¹, M. Thürauf¹, N. Pietralla¹, C. Bernads², A. Blanc³, R.B. Cakirli⁷, R.F. Casten², N. Cooper², G. de France⁸, M. Jentschel³, J. Jolie⁶, U. Köster³, P. Mutti³, R.B. Régis⁶, M Scheck⁵, G. Simpson⁵, W. Urban⁴, and D. Wilmsen⁶ — ¹TU Darmstadt — ²Yale University — ³Institut Laue-Langevin — ⁴University of Warsaw — ⁵University of West Scotland — ⁶Universität zu Köln — ⁷University of Istanbul — ⁸Grand Accélérateur National d’Ions Lourds

A crossing of the deformations of the ground state and the band head of the K=0 (β) band had been observed in the Gadolinium isotopic chain at N=90, where a phase transition from spherical to deformed shapes occurs. As a consequence past N=90 the first excited 0⁺ state has a smaller β-deformation than the ground state. However, it has been predicted that the deformations of both states should become similar in the deformed limit. To test this prediction in ¹⁵⁸Gd, we performed an experiment within the EXILL (n, γ) campaign at the Institut Laue-Langevin in Grenoble. Excited states in ¹⁵⁸Gd were populated after neutron capture, and we searched for the 64 keV 2₃⁺ → 0₂⁺ γ -decay within the K=0 band. A weak signal of the transition of interest has been identified in the γ γ coincidence matrix, which allows to constrain the shape of the 0₂⁺ state.

Supported by DFG Grant SFB 634 und U.S.DOE Grant No. DE-FG02-91ER40609