# The $\gamma-\gamma$ fast-timing technique and the EXILL&FATIMA campaign

Abstract : At the Institut Laue-Langevin in Grenoble, germanium-gated γ-γ fast-timing lifetime measurements of nuclear excited states in neutron-rich nuclei have been performed within a prompt γ-ray spectroscopy experimental campaign. We report on results obtained from the cold-neutron induced fission of 235U. The excited secondary fission products were stopped almost instantaneously within the thick target and the γ rays emitted were collected triggerlessly using the EXILL&FATIMA mixed array of HPGe and LaBr3(Ce) detectors. Precise lifetimes could be determined by analysing the γ-γ time difference spectra using the generalized centroid difference method. This picosecondsensitive method provides many advantages and is briefly explained. Still, the major source of systematic errors is related to the contribution of time-correlated Compton background. The EXILL&FATIMA results are discussed with respect to the typical energy-dependent timing behaviour of the background. According to the time response of the background, appropriate methods and a time correction for the sub-nanosecond regime are proposed.
Type de document :
Communication dans un congrès
6th Workshop on Nuclear Fission and Spectroscopy of Neutron-Rich Nuclei, Mar 2017, Chamrousse, France. EPJ Web Conf., 193, pp.04008, 2018, 〈10.1051/epjconf/201819304008〉

https://hal.archives-ouvertes.fr/hal-01952148
Contributeur : Inspire Hep <>
Soumis le : mardi 11 décembre 2018 - 21:07:30
Dernière modification le : mardi 19 mars 2019 - 21:06:48

### Citation

J.-M. Régis, G.S. Simpson, H. Mach, A. Blanc, M. Jentschel, et al.. The $\gamma-\gamma$ fast-timing technique and the EXILL&FATIMA campaign. 6th Workshop on Nuclear Fission and Spectroscopy of Neutron-Rich Nuclei, Mar 2017, Chamrousse, France. EPJ Web Conf., 193, pp.04008, 2018, 〈10.1051/epjconf/201819304008〉. 〈hal-01952148〉

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