High-speed position encoding system for the TPC with micro pixel chamber readout

For the readout of the time projection chamber with our developed micro-pattern gaseous detector (micro-PIC), we have developed a high-speed position encoding system operated at 100 MHz clock, by combination of multi-channel analog-ASIC preamplifiers, a position encoding system with FPGA processors, a VME-bus memory-board, and a VME-bus CPU. This system has inputs for the 768 anodes and 768 cathodes channels. The LVDS output from a comparator in the ASIC preamplifier is synchronized in a FPGA, and the two dimensional position of drifting electrons is calculated in the FPGAs at 100 MHz with coincidence of anodes and cathodes. The depth position of the track is calculated with the drift velocity and the elapsed time from the external trigger. With this system, we have successfully obtained the three dimensional track in the TPC.