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Description
This study aims at understanding the dependence of the E1 strength in the transition region from vibrational to rotational nuclei. Below the Z = 50 closed shell Sn nuclei, week deformations start to build in. In the case of 106Pd, the observed band structures were reported to correspond to a quadrupole deformation of β2 = 0.175 [1], where calculations within the tilted-axis cranking model [2] were presented. The low-lying E1 states in the transitional Pd nuclei are expected to be weak and strongly fragmented. The chosen method of study is the Nuclear Resonance Fluorescence(NRF) [3] method, a two-step photonuclear process which consists of the absorption of a photonand the subsequent resonant re-emission of gamma rays.
An NRF experiment was conducted at TU Darmstadt, using the DHIPS (Darmstadt High-Intensity Photon Source) setup. A monoenergetic electron beam, with a current of 40 μA, impinging on two Ag bremsstargets (1mm and 5 mm thickness) and creating bremsstrahlung radiation was employed. The endpoint energy was situated at 8.7 MeV. An array of three high-purity Germanium (HPGe) detectors, positioned at 130◦ and two at 90◦ with respect to the incoming beam, was employed. They were equipped with bismuth germanate (BGO) shields for active Compton suppression and additionally mounted in lead collimators. The primary target consists of 0.991 g of
106Pd and was placed in between the three detectors.
This first measurement on 106Pd uncovered new transitions in the 3.5-8 MeV energy range. The data is currently being analyzed and will provide an overview of the γ-ray transition energies, integrated cross-sections and reduced transition strengths.
References:
[1] C.E. He et al., Phys. Rev. C 86, 047302 (2012);
[2] S. Frauendorf, Nucl. Phys. 557, 259c (1993);
[3] L.I. Schiff, Phys. Rev. 70, 761-762 (1946).
*This work is supported by Project ELI-RO/DFG/2025_013 IATP-NP 2.0 funded by the Institute of Atomic Physics, Romania and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 499256822 – GRK 2891 “Nuclear Photonics”.