Comparative measurements on LaBr/sub 3/(Ce) and LaCl/sub 3/(Ce) scintillators coupled to PSPMT

Lanthanum halide detector energy resolution measurements at 662 keV for a LaBr/sub 3/ crystal (3.67%) and a 6 /spl times/ 6 array of LaCl/sub 3/ crystals (4.65%) coupled to a 5'' diameter Hamamatsu PSPMT are compared to measurements on arrays of NaI (7.37%) and BGO (16.07%). The uncorrected energy resolution using the entire LaCl/sub 3/ array is poor (13%) due to weaker responses from the edge pixels, but is improved to 5.85% with a position dependent gain correction. Spectra are presented from a well-collimated source focused upon a small area of the detector, as well as uncollimated 2D flood-fields.