The Generalized Centroid Difference method for lifetime measurements via γ-γ coincidences using large fast-timing arrays

A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via γ-γ coincidences using an array equipped with N very fast high-resolution LaBr3(Ce) scintillator detectors is presented. The generalized centroid difference method provides two independent “start”...

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Hauptverfasser: Régis, J.-M., Jolie, J., Mach, H., Simpson, G.S., Blazhev, A., Pascovici, G., Pfeiffer, M., Rudigier, M., Saed-Samii, N., Warr, N., Blanc, A., de France, G., Jentschel, M., Köster, U., Mutti, P., Soldner, T., Ur, C.A., Urban, W., Bruce, A.M., Drouet, F., Fraile, L.M., Ilieva, S., Korten, W., Kröll, T., Lalkovski, S., Mărginean, S., Paziy, V., Podolyák, Zs, Regan, P.H., Stezowski, O., Vancraeyenest, A.
Format: Tagungsbericht
Sprache:eng
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Zusammenfassung:A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via γ-γ coincidences using an array equipped with N very fast high-resolution LaBr3(Ce) scintillator detectors is presented. The generalized centroid difference method provides two independent “start” and “stop” time spectra obtained without any correction by a superposition of the N(N – 1)/2 calibrated γ-γ time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific γ-γ cascade and the centroid difference as the time shift between the centroids of the two time spectra provides a picosecond-sensitive mirror-symmetric observable of the set-up. The energydependent mean prompt response difference between the start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing array mean γ-γ zero-time responses can be determined for 40 keV < Eγ < 1.4 MeV with a precision better than 10 ps using a 152Eu γ-ray source. The new method is described with examples of (n,γ) and (n,f,γ) experiments performed at the intense cold-neutron beam facility PF1B of the Institut Laue-Langevin in Grenoble, France, using 16 LaBr3(Ce) detectors within the EXILL&FATIMA campaign in 2013. The results are discussed with respect to possible systematic errors induced by background contributions.
ISSN:2100-014X
2101-6275
2100-014X
DOI:10.1051/epjconf/20159301013