Characterization of Sodium Iodide Scintillation Detectors on the Basis of Positional Response*

The Texas CsI Array for Astrophysical Measurements(TexCAAM) is a gamma-ray spectroscopy tool that is currently being utilized at the Texas A&M University Cyclotron Institute. However, recent access to  large volume sodium iodide(NaI) detectors has created the motivation to replace the current experimental set up of the CsI detectors. These NaI scintillation detectors have the potential to produce significantly better energy resolution and timing resolution  than CsI detectors. However, in order for this replacement to occur, these particular large volume NaI detectors must be characterized on the basis of positional response. To be useful,  the photopeak height and energy resolution should not depend significantly on the interaction location.This characterization has been  done through the use of two different gamma-ray sources for the sake of completeness, Cobalt-60 and Cesium-137. The differences in the photopeak channel readout across the faces of these detectors is normalized to  visually show the variation from a chosen reference point. The test results show that the detectors have a typical resolution of 5.11-11.0% with pulse-height dependence of 1.6-6.4% as per manufacturer specifications. Additional results explore how individual detectors perform.