Heidelberg 2015 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 26: Structure and Dynamics of Nuclei 6
HK 26.6: Vortrag
Dienstag, 24. März 2015, 16:00–16:15, T/SR14
Investigation of two-phonon 1− states in 40Ca and 140Ce with the γ3 setup at HIγS — •Julius Wilhelmy1, Vera Derya1, Janis Endres1, Andreas Hennig1, Bastian Löher2,3, Deniz Savran2,3, Werner Tornow4, and Andreas Zilges1 — 1Institute for Nuclear Physics, University of Cologne — 2ExtreMe Matter Institute EMMI and Research Division, GSI, Darmstadt — 3Frankfurt Institute for Advanced Studies FIAS, Frankfurt — 4Department of Physics, Duke University, USA
The harmonic coupling of a quadrupole and an octupole vibrational excitation results in a quintuplet of Jπ=1− to 5− vibrational states at the sum of the constituent excitation energies. Their detailed γ-decay behavior can provide information about their structure. For 40Ca and 140Ce, possible two-phonon E1 excitations were studied with the high-efficiency γ3 setup [1] at the High Intensity γ-ray Source facility at TUNL in Durham, USA. The γ3 setup consists of an array of HPGe and LaBr3 detectors with high efficiency and enables the measurement of γ-γ coincidences. The determination of the B(E2; 11− → 31−) value was possible showing a dominant two-phonon character of the 11− state in 40Ca. For the same decay in 140Ce, an upper limit for the reduced transition probability can be given and an unexpected E1 decay to the 02+ state was observed. The experimental results will be presented and discussed with regard to systematics and theoretical predictions. Supported by the DFG (ZI 510/4-2) and the Alliance Program of the Helmholtz Association (HA216/EMMI).
[1] B. Löher et al., Nucl. Instr. and Meth. A 723 (2013) 136