described by O'Neill et. al. two years ago. The energy resolution provided by these detectors, although very good (-1.5-2% FWHM in the range 1-15 GeV), appeared to be limited by an optical discontinuity at the interface between the two 30 in. diameter by 10 in. thick crystal blanks from which each of these detectors was assembled. In the absence of this discontinuity the energy resolution was expected to be limited by fluctuations in energy leakage from the crystal volume, which for these detectors was computed to produce a line-width of close to 1% FWHM in the range 1-15 GeV. Despite their good energy resolution, the utility of these 30 in. diameter NaI(TQ) detectors is limited in high energy physics applications, as pointed out by