Commissioning of the LaBr_3(Ce) detector array at the National Superconducting Cyclotron Laboratory

摘要

The timing and energy resolution properties of LaBr3(Ce) scintillators are well suited for use in gamma gamma fast-timing experiments. Using standard Co-60, Y-88, and Eu-152 sources, the 16-element array of 1.5 inch x 1.5 inch right-cylindrical LaBr3(Ce) detectors and the associated readout electronics at the National Superconducting Cyclotron Laboratory were commissioned by measuring the lifetimes of excited states and the angular correlations of gamma rays emitted in cascade. Excited-state lifetimes in Sm-152 and Gd-152 were measured using the exponential slope of the decay and a method based on the centroids of time-difference spectra. Results for the lifetimes are consistent with the well-known literature values which cover a range from a few picoseconds to several nanoseconds. Furthermore, the gamma gamma angular correlations for the 4(+) - 2(+) - 0(+) cascade in Ni-60 and the 3(-)- 2(+) - 0(+) cascade in Sr-88 were measured and shown to agree with GEANT4 simulations that take into account the expected angular correlations within the cascades as well as the geometry of the array.