Bochum 2018 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 18: Structure and Dynamics of Nuclei III

HK 18.3: Talk

Tuesday, February 27, 2018, 14:45–15:00, HZO 70

Nuclear structure of ⁸²Se and ⁸²Kr relevant for 0ν β β decay — •Udo Gayer¹, Tobias Beck¹, Jörn Kleemann¹, FNU Krishichayan², Bastian Löher¹, Oliver Papst¹, Norbert Pietralla¹, Philipp Christian Ries¹, Deniz Savran³, Michael Weinert⁴, Werner Tornow², and Volker Werner¹ — ¹IKP, TU Darmstadt — ²Duke University, Durham NC, USA — ³GSI, Darmstadt — ⁴IKP, Universität zu Köln

The nuclei ⁸²Se and ⁸²Kr are candidates for the hypothetical neutrinoless double-beta (0 ν β β) decay process, and a precise knowledge of their nuclear structure is necessary to estimate decay rates and extract neutrino properties from a possible observation. Therefore, we have studied the decay properties of low-lying dipole excitations up to 4.2 MeV in both isotopes in a nuclear resonance fluorescence experiment with quasi-monoenergetic, polarized photons at the High-Intensity Gamma-Ray Source (HIγS). The experiment used the γ³ setup [1] and a second setup with four HPGe detectors for a simultaneous measurement of ⁸²Se and ⁸²Kr. In this energy range, several dipole excitations were newly identified, and their relative excitation strengths were estimated from nonresonant scattering off the targets. Transitions of 1⁺ scissors mode states to lower-lying excited states with branching ratios as low as 1 % were observed, which can give an insight into shape coexistence effects [2]. Results of the experiment will be presented and interpreted.
*Supported by DFG research grant SFB 1245
B. Löher et al., NIMA 723 (2013) 136-142
J. Beller et al., Phys. Rev. Lett. 111 (2013) 172501