Investigation on XRay Photocurrent Response of CdZnTe Photon Counting Detectors Counting rate is an important factor for CdZnTe photon counting detectors as highflux devices. Until recently, there has been a lack of knowledge on the relationship between Xray photocurrent response and the photon counting performance of CdZnTe detectors. In this paper, the performance of linear array 1 xc3x97 16pixel CdZnTe photon counting detectors operated under different applied biases is investigated. The relation between experimental critical flux and applied bias show an approximate quadratic dependence, which agrees well the theoretical prediction. The underlying relationship among Xray photocurrents, carrier transport properties, and photon counting performance was obtained by analyzing Xray currentxe2x80x93voltage and time current curves. The typical Xray photocurrent curve can be divided into three regions, which may be explained by the photoconductive gain mechanism and electric field distortion characteristics. To keep CdZnTe photon counting detectors working in a xe2x80x9cnonpolarized statexe2x80x9d, the applied bias should be set on the left side of the xe2x80x9cvalley regionxe2x80x9d (high bias direction) in the Xray IV curves. This provides an effective measurement for determining the proper working bias of CdZnTe detectors and screening photon counting detector crystals.

A full functional Monolithic Active Pixel Sensor prototype for the CEPC vertex detector The proposed Circular ElectronPositron Collider (CEPC) presents new challenges for pixel detectors in terms of cell size and functionality. A high data rate digital design and readout architecture of a Monolithic Active Pixel Sensor (MAPS) prototype for the CEPC vertex detector is presented. The MAPS prototype, together with the column drain based readout architecture, benefiting from the ALPIDE (ALice PIxel DEtector) and FEI3 approaches, has been implemented to achieve high spatial resolution, fast readout, and low power consumption. The simulation results indicate the readout logic works properly with input data rates of 120MHz; while both analog frontend and inpixel readout logic meet the 25ns bunch spacing constraint.