TY  - THES
AU  - Löher, Bastian
TI  - Probing the decay characteristics of the Pygmy Dipole Resonance in the semi-magic nucleus <sup>140</sup>Ce with γ-γ coincidence measurements
PB  - Johannes Gutenberg-Universität Mainz
VL  - Dissertation
M1  - GSI-2014-01533
SP  - 127 p.
PY  - 2014
N1  - Dissertation, Johannes Gutenberg-Universität Mainz, 2014
AB  - This work presents the design and installation of a novel experimental setup - the γ<sup>3</sup> setup - for measuring photon-induced nuclear dipole excitations in stable isotopes at the High Intensity γ-ray Source (HIγS) at the Duke University. The high energy resolution and high detection efficiency of the detector array, consisting of a combination of LaBr and HPGe detectors, allows for the first time the efficient measurement of γ³-γ³-coincidences in combination with the method of nuclear resonance fluorescence. This technique provides access to the decay pattern of dipole excited states as an additional observable, which allows a deeper insight into the underlying structure of these excitations. The experimental setup has already been used successfully for two experimental campaigns in 2012 and 2013 in the investigation of 13 different target isotopes. Within the scope of this thesis the Pygmy Dipole Resonance (PDR) of 140Ce was studied in the excitation energy range from 5.2 MeV to 8.3 MeV based on data obtained with the γ3 setup. In particular the decay pattern of the states participating in the PDR was investigated. The experimental setup, the details of the analysis and the experimental results are presented in this thesis. A comparison of the results to theoretical quasi-particle phonon model (QPM) calculations allows for an interpretation of the observed decay behaviour.
KW  - Dissertation (GND)
LB  - PUB:(DE-HGF)11
UR  - https://repository.gsi.de/record/66641
ER  -