Lately there has been a gradual migration of the system from central processing facilities towards clusters of workstations. Diehl et al. The instrument consists of two detector layers. Each detector layer is surrounded by anticoincidence shields to reject charged-particle events. Relative PMT signals define the scatter and absorption location in the instrument.
Total signals define the energy.
These parameters allow computation of scatter direction and scatter angle of the photon. A maximum of 20 events per second can be registered. For each event all relevant PMT signals, anticoincidence signals, time of flight between D1 and D2 and a few other parameters are recorded, which results in a continuous stream of data of about 1 kbytes per second, about 30 Gbyte per year. These data are exported to all sites of the collaboration for further analysis. Four sites at widely separated places having a great variety of computer hardware had to work closely together.