Refinement of position resolution in two-dimensional X-ray detector based on μ-PIC gaseous detector

We have successfully refined the position resolution of a two-dimensional X-ray photon-counting detector based on the micro-pixel gas chamber (mu-PIC) by measuring the charge distribution of an X-ray interaction without the use of analog-to-digital converters (ADCs). By updating the logic of the Field Programmable Gate Arrays (FPGAs) included in the data acquisition system, we were able to acquire the pulse widths, or time-above-threshold of the mu-PIC signals, by measuring both the leading and trailing edges of the digital signals. By using the measured widths to estimate the peak of the charge distribution, the position resolution of our detector was improved to sigma = 93.3 +/- 2.8 mu m from a value of sigma = 229.5 +/- 6.8 mu m found using the FPGA logic of the previous system. This represents an improvement of nearly 60%. (C) 2012 Elsevier B.V. All rights reserved.