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Abstract: In this paper, we present the design and preliminary performance evaluation of a novel energy-resolved photon-counting (ERPC) detector for gamma ray imaging applications. The prototype ERPC detector has an active area of 4.4cm×4.4cm, which is pixelated into 128×128 square pixels with a pitch size of 350μm×350μm. The current detector consists of multiple detector hybrids, each with a CdTe crystal of 1.1cm×2.2cm×1mm, bump-bonded onto a custom-designed application-specific integrated circuit (ASIC). The ERPC ASIC has 2048 readout channels arranged in a 32×64 array. Each channel is equipped with pre- and shaping-amplifiers, a discriminator, peak/hold circuitry and an analog-to-digital converter (ADC) for digitizing the signal amplitude. In order to compensate for the pixel-to-pixel variation, two 8-bit digital-to-analog converters (DACs) are implemented into each channel for tuning the gain and offset. The ERPC detector is designed to offer a high spatial resolution, a wide dynamic range of 12–200keV and a good energy resolution of 3–4keV. The hybrid detector configuration provides a flexible detection area that can be easily tailored for different imaging applications. The intrinsic performance of a prototype ERPC detector was evaluated with various gamma ray sources, and the results are presented. [Copyright &y& Elsevier]