FPGA-based Time to Digital Converter and Data Acquisition system for   High Energy Tagger of KLOE-2 experiment
  In order to reconstruct gamma-gamma physics events tagged with High Energy Tagger (HET) in the KLOE-2 (K LOng Experiment 2), we need to measure the Time Of Flight (TOF) of the electrons and positrons from the KLOE-2 Interaction Point (IP) to our tagging stations (11 m apart). The required resolution must be better than the bunch spacing (2.7 ns). We have developed and implemented on a Xilinx Virtex-5 FPGA a Time to Digital Converter (TDC) with 625 ps resolution (LSB) along with an embedded data acquisition system and the interface to the online FARM of KLOE-2. We will describe briefly the architecture of the TDC and of the Data AcQuisition (DAQ) system. Some more details will be provided about the zero-suppression algorithm used to reduce the data throughput. 
L. Iafolla, A. Balla, M. Beretta, P. Ciambrone, M. Gatta, F. Gonnella,   M. Mascolo, R. Messi, D. Moricciani, D. Riondino
physics.ins-det hep-ex