Bochum 1998 – scientific programme

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HK: Hadronen und Kerne

HK 50: Spectroscopy: 130 ≤ A ≤ 180

HK 50.2: Talk

Wednesday, March 18, 1998, 14:30–14:45, D

Observation of a possible mixed–symmetry state in ¹²⁶Xe — •A. Gade¹, I. Wiedenhöver², H. Meise¹, A. Dewald¹, J. Gableske¹, H. Klein¹, A. Gelberg¹, and P. von Brentano¹ — ¹Institut für Kernphysik, Universität zu Köln — ²Argonne National Laboratory, Argonne, IL, USA

Non yrast low spin states in ¹²⁶Xe were populated by the ¹²³Te (α,n) ¹²⁶Xe reaction at the Cologne fn tandem accelerator. γγ coincidences and γ–singles spectra were measured with the Osiris-cube spectrometer. γγ angular correlations were analyzed to assign spins and parities to the excited states, and to determine the multipolarities of the γ–transitions. We found a dominant M1–decay depopulating the 2₄⁺ state at 2064 keV. Furthermore the multipole mixing ratio δ(2₄⁺ → 2₁⁺) was determined and a DSAM analysis yielded the lifetime τ(2₄⁺). From δ and τ we obtained the absolute B(M1) value B(M1; 2₄⁺ → 2₁⁺). The observed strong M1–decay is interpreted as due to the lowest 2⁺ mixed–symmetry state. A comparison with the results of an IBM–2 calculation will be presented.
Supported by DFG, Project No. Br 799/8–1