Measurement of the Isolated Nuclear Two-Photon Decay in $^{72}\mathrm{Ge}$

Author:

D. Freire-Fernández, W. Korten, R. J. Chen, S. Litvinov, Yu. A. Litvinov, M. S. Sanjari, H. Weick, F. C. Akinci, H. M. Albers, M. Armstrong, A. Banerjee, K. Blaum, C. Brandau, B. A. Brown, C. G. Bruno, J. J. Carroll, X. Chen, Ch. J. Chiara, M. L. Cortes, S. F. Dellmann, I. Dillmann, D. Dmytriiev, O. Forstner, H. Geissel, J. Glorius, A. Görgen, M. Górska, C. J. Griffin, A. Gumberidze, S. Harayama, R. Hess, N. Hubbard, K. E. Ide, Ph. R. John, R. Joseph, B. Jurado, D. Kalaydjieva, K. Kanika, F. G. Kondev, P. Koseoglou, G. Kosir, Ch. Kozhuharov, I. Kulikov, G. Leckenby, B. Lorenz, J. Marsh, A. Mistry, A. Ozawa, N. Pietralla, Zs. Podolyák, M. Polettini, M. Sguazzin, R. S. Sidhu, M. Steck, Th. Stöhlker, J. A. Swartz, J. Vesic, P. M. Walker, T. Yamaguchi, R. Zidarova

Keyword:

Nuclear Experiment, Nuclear Experiment (nucl-ex), Nuclear Theory (nucl-th)

journal:

date:

2023-12-18 00:00:00

Abstract

The nuclear two-photon or double-gamma ($2\gamma$) decay is a second-order electromagnetic process whereby a nucleus in an excited state emits two gamma rays simultaneously. To be able to directly measure the $2\gamma$ decay rate in the low-energy regime below the electron-positron pair-creation threshold, we combined the isochronous mode of a storage ring with Schottky resonant cavities. The newly developed technique can be applied to isomers with excitation energies down to $\sim100$\,keV and half-lives as short as $\sim10$\,ms. The half-life for the $2\gamma$ decay of the first-excited $0^+$ state in bare $^{72}\mathrm{Ge}$ ions was determined to be $23.9\left(6\right)$\,ms, which strongly deviates from expectations.

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