A Study on Time-Of-Flight FPGA for Associated Particle Imaging

In this paper, we presented the field programmable gate array (FPGA) technique which is intended to measuring time-of-flight (TOF) that can determine the distance which is produced by the associated particle imaging (API) techniques including neutron methods with neutron generator and secondary radiation detection. The API method is the neutron-based technologies for the elemental analysis. We used the propagation delay on the internal wires of FPGA chips to generate TOF scheme. The measure is based on the comparison between the operating frequencies of two ring oscillators that differ within 100 ps. Experimental timing results were generated with a device of the Xilinx vertex family. The period difference of these two ring oscillators of FPGA is about 100 ps, the timing resolution of TDC. After implementation of TDC, TOF schemes such as time stamp and control logic were generated. Finally, we evaluated that the TOF FPGA was useful in the multi channel analyzer (MCA) to measure the time difference between α-γ of API system.