6 MeV energy calibration and reconstruction with pixelated CZT detectors using digital methods

CZT is an attractive material for gamma-ray spectroscopy due to its high resolution, high efficiency and ability to operate at room temperature. It has shown better than 1 % FWHM energy resolution at 662 keV. However, at higher energies, the electron cloud gets bigger than the size of a single pixel. This effect is known as charge sharing and contributes to energy resolution degradation. It is important for planetary science and astrophysics applications to broaden the energy range of pixelated CZT detectors. A digitizer system was used to study the response of a 2 cm × 2 cm × 1.5 cm pixelated CZT detector manufactured by Redlen Technology Inc., to a source of 6.129 MeV from the de-excitation of the second excited state of ¹⁶O. The 5.107 MeV double escape peak was identified and has shown that the response of the system is linear at high energy.