CHARACTERIZATION OF A PROTOTYPE PIXEL ARRAY DETECTOR (PAD) FOR USE INMICROSECOND FRAMING TIME-RESOLVED X-RAY-DIFFRACTION STUDIES

A 4 by 4 pixel array device has been designed and built as a prototype for a high-speed two-dimensional x-ray imaging detector. This detecto r is a two-tier device, with an x-ray sensitive photo-diode array bump -bonded to a 1.2 micrometer CMOS analog integrated circuit. Each 150 m icrometer square pixel of the detective layer is matched to a correspo nding section of the electronics. Each pixel of the electronics is cap able of integrating the signal from the diode for the desired framing time, storing the result in one of eight storage capacitors, and seque ntially outputting the stored value to an on-chip buffering op-amp. Te sts of the electronics have demonstrated a full-well (per pixel, per f rame) of over 10,500 12 keV x-rays with an electronics noise level cor responding to less than 2.8 12keV x-rays. Speed tests indicate the abi lity to integrate to the full-well within 2 microseconds (an average p ixel 'count-rate' of 5.2 GHz). We present detailed characterizations o f the performance of this initial device, including an analysis of noi se, stability, linearity and point-spread. In addition, we will discus s plans for large-scale integration towards the goal of a 1024 by 1024 pixel detector.