Darmstadt 2016 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 13: Structure and Dynamics of Nuclei IV
HK 13.5: Vortrag
Montag, 14. März 2016, 17:45–18:00, S1/01 A04
Lifetimes of excited states in neutron-rich Xe isotopes — •Stoyanka Ilieva and Thorsten Kroell for the EXILL-FATIMA collaboration — Institut für Kernphysik, TU Darmstadt
The EXILL&FATIMA campaign at ILL, Grenoble is the first prompt-fission γ-ray spectroscopy experiment performed with a mixed array of Ge detectors (EXILL) and fast LaBr3(Ce) scintillators (FATIMA). The lifetimes of excited states, populated by neutron-induced fission of 235U and 241Pu targets, were directly measured. The high-resolution EXILL detector gives us the possibility to identify the nuclides of interest among the large amout of produced fission fragments. Using the generalized centroid difference method [1] to analyse the data from FATIMA we could measure lifetimes down to ≈ 10 ps.
The lifetime of an excited state is a direct measure for the strength (collectivity) of a transition. The properties of the excited states in even-even nuclei can be largely described by quadrupole and octupole degrees of freedom. This contribution will present the current status of the analysis for the neutron-rich even-even 138,140,142Xe isotopes which lie in the vicinity of the double shell closure Z=50 and N=82. Through the direct lifetime measurement we aim to study the evolution of quadrupole and octupole collectivity above 132Sn.
[1] J.-M. Régis et al., NIM A 763 (2014) 210
Supported by ILL, by BMBF under contracts 05P12RDCIA and 05P12RDNUP, and by HIC for FAIR.