Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 29: Nuclear Structure/Spectroscopy V

HK 29.1: Group Report

Wednesday, March 10, 2004, 14:00–14:30, A

Test of the critical point symmetry X(5) in the A=150,180 mass regions — •A. Dewald¹, O. Möller¹, A. Fitzler¹, B. Saha¹, D. Tonev¹, K. Jessen¹, J. Jolie¹, K.O. Zell¹, P. von Brentano¹, P Petkov², N. Marginean³, M. Axiotis³, D. Bazzacco⁴, S Lunardi⁴, C.A. Ur⁴, R. Menegazzo⁴, and E. Farnea⁴ — ¹IKP Universität zu Köln, Germany — ²Bulg.Acad. of Science, INRNE, Sofia, Bulgaria — ³INFN, LN Legnaro, Italy — ⁴University and INFN Padova,Padova, Italy

We will report on investigations aiming for stringent tests of the new critical point symmetry X(5) predictions [1] for the N=90 nuclei ¹⁵⁴Gd and ¹⁵⁶Dy. Aside from the energy spectra, absolute transition probabilities are crucial observables. We will compare our latest experimental values with the X(5) calculations as well as with IBM and GCM fits. Based on the energy spectra and relative transition probabilities, the ^176−180Os nuclei can be considered to be very promising X(5) candidates in a new mass region. In oder to perform stringent tests for these Os nuclei more experimental data on absolute transition probabilities are needed. Therefore we performed a coincidence plunger measurement with the GASP spectrometer and the Köln plunger device. First results will be presented and compared to X(5) and IBA calculations.
[1] F. Iachello, Phys. Rev. Lett.. 87, 52502 (2001)
Supported by the BMBF project no. 06K-167 and under the Eu Programme contract no. HPRI–CT-1999-00083