Overview of the T2K fine grained detector data acquisition at J-Parc

The Fine Grained Detector (FGD) is one of the sub-systems of the T2K experiment at J-PARC. The trajectories of charged particles produced by neutrinos interacting within the FGD will be reconstructed and used to determine the neutrino interaction point and the neutrino energy, together with other detectors. The FGD also provides some particle identification capabilities by measuring energy loss. The FGD consists of 8448 scintillator bars read out by wavelength-shifting fiber coupled to Multi-Pixel Photon Counters (MPPC). The FGD active volume is surrounded by 3 different boards: Frontend Boards (FEB) which use the SCA ASIC (AFTER) for waveform recording, the Crate Master Board (CMB) for local data collection, and the Light Pulser Boards for calibration purposes are surrounding the active volume of the FGD. The data are then sent by optical links to the Data Concentrator Cards (DCC), then by Ethernet link to the back-end computer. The FGD has the capability to generate a trigger which is sent through LVDS links to the main Trigger module. The monitoring of all the on-detector electronics is managed by means of an independent data path using the Midas Slow-Control Bus (MSCB).