Intelligent gamma-ray spectroscopy using 3D position-sensitive detectors

The performance of gamma-ray spectrometers at high energies (several MeV) can he greatly improved through intelligent spectroscopic analysis if spatial information is obtained for each energy deposition. In position-sensitive detectors, the energy and three-dimensional position of each interaction in the detector are determined. Recognizing the signatures of multiple interactions in the detector can help to reconstruct the energies of the initial gamma rays even when the full energies are not deposited. We present the results of a simulation study for 2.6 MeV gamma rays incident upon a 6-cm³ CdZnTe detector using two reconstruction methods: high efficiency intelligent spectroscopy (HEIS) in which the peak-to-total ratio is greatly improved relative to traditional spectroscopy while maintaining almost the same intrinsic peak efficiency; and peak-only intelligent spectroscopy (POIS) in which the peak-to-total ratio can approach 0.9, assuming realistic values for energy resolution. Although POIS reduces the intrinsic peak efficiency, it will significantly improve the signal-to-noise ratio for many measurements. The predicted performance is unprecedented for a detector of such small volume and illustrates the gains that can be expected by exploiting 3-D information.