2 Energy resolution

A set of X-ray and gamma-ray lines from 14 to 184 keV were measured by the anodes of the prototype detector (Fig. 2). The lines are Gaussian-like at all energies. Energy resolution is $\sim$3 keV at low energies, increasing to $\sim$6 keV at high energies. These profiles are in marked contrast to those typically obtained in planar CZT detectors above $\sim$60 keV, where incomplete charge collection due to hole trapping results in tailing and poor spectral performance. The prototype detector's performance is similar to "spectrometer grade'' CZT, which is expensive and only available in small sizes, $\sim$1 cm. However, it is made of inexpensive "discriminator grade'' CZT, which is available in large sizes, e.g., 32 mm. Our advanced techniques produce spectrometer grade performance from discriminator grade material.

  

Figure 2: Line profiles and FWHM energy resolution at several energies. All were measured with discrete laboratory electronics (Amptek A-250 preamps) except the 14 keV line which was measured with the RENA-type ASIC