Heidelberg 2015 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 26: Structure and Dynamics of Nuclei 6

HK 26.2: Talk

Tuesday, March 24, 2015, 15:00–15:15, T/SR14

Quadrupole decay strength of the M1 scissors mode of ¹⁵⁶Gd⋆ — •T. Beck¹, J. Beller¹, V. Derya², U. Gayer¹, J. Isaak^3,4, B. Löher^3,4, L. Mertes¹, H. Pai¹, N. Pietralla¹, P. Ries¹, C. Romig¹, D. Savran^3,4, M. Scheck^1,5,6, W. Tornow⁷, H.R. Weller⁷, V. Werner¹, and M. Zweidinger¹ — ¹IKP, TU Darmstadt — ²IKP, Universität zu Köln — ³EMMI, GSI, Darmstadt — ⁴FIAS, Frankfurt — ⁵School of Engineering, UWS, Paisley, UK — ⁶SUPA, Glasgow, UK — ⁷Duke University, Durham, USA

The isovector low-lying J_K^π=1₁⁺ scissors mode of deformed nuclei has been studied extensively in (e,e’) and (γ,γ’) experiments over the last 30 years with the main focus on strong M1 transitions to the ground state band. In the framework of the semiclassical two-rotor-model it has its origin in quadrupole deformation. A considerable E2 matrix element between the rotational band of the scissors mode and the ground band is predicted which has not been addressed experimentally. A photon-scattering experiment with linearly-polarized quasi monoenergetic γ^→-rays has been performed at the High Intensity γ^→-ray Source (HIγ^→S) at Duke University, Durham, NC, exploiting the γ³ setup. We have measured an E2/M1-multipole mixing ratio for the 1_sc⁺→2₁⁺ transition for the first time. The Alaga rule is applicable and delivers a first estimate of the transition strength B(E2:2_sc⁺→0₁⁺ ). A candidate for a 2_sc⁺→2₁⁺ transition will be discussed.
⋆ Supported by the DFG within the scope of SFB 634