Erlangen 2026 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 22: Structure and Dynamics of Nuclei VI
HK 22.5: Vortrag
Mittwoch, 18. März 2026, 15:15–15:30, AM 00.021
Chasing the elusive nuclear two-photon decay in 72Ge — •Michael Weinert1, Wolfram Korten2, Yury Litvinov1,3, Markus Müllenmeister1, Peter Reiter1, and Andreas Zilges1 — 1University of Cologne, Institute for Nuclear Physics, Germany — 2IRFU, CEA, Université Paris-Saclay, France — 3GSI Helmholtzsentrum für Schwerionenforschung, Darmstadt, Germany
A recent study at the ESR storage ring at GSI, Darmstadt, allowed to indirectly observe the nuclear two-photon (2γ) decay of the first excited state in 72Ge [1]. By storing the excited and fully ionized nucleus in the ESR, conventional electron conversion can no longer depopulate the 0+ isomer and the rare second-order electromagnetic process becomes the dominant decay path. It could be shown that the isomeric state has a much longer, yet finite lifetime in the ESR system, serving as an indirect observation of the 2γ decay. This contribution presents the current endeavors on complementary 72Ge(p,p′γ) experiments, hunting for the direct observation of this extremely rare decay process. Besides finding a way to strongly populate the isomeric state, several orders of magnitude of natural and beam induced γ-ray background have to be suppressed. An overview of the latest experiments witht he SONIC@HORUS setup in Cologne [2] and with the ELIFANT array [3] at IFIN-HH, Bucharest, will be given.
[1] D. Freire-Fernández et al., Phys. Rev. Lett. 133, 022502 (2024)
[2] S. G. Pickstone et al., Nucl. Inst. Meth. A 875 (2017) 104-110
[3] D. L. Balabanski et al., EPJ Web Conf. 342, 01002 (2025)
Keywords: two-photon decay; second order decay; low-background measurement; 72Ge(p,p'g)