DAQ system for the readout of silicon pixel detectors based on VataGP7 front-end ASIC

High resistivity silicon is a competitive material for photon detectors. Its excellent spatial and energy resolution make them attractive to be used as second detector in medical physics applications. A stack of several detector layers would significantly improve the low stopping power of a single detector. This however, increases considerably the number of channels to be read-out. A Data acquisition system (DAQ) has been developed at IFIC - Valencia to cope with a stack of such detectors. The system is based on the 128 channels VATAGP7 application specific integrated circuit (ASIC) from Gamma Medica - Ideas. A dedicated electronic board (MADDAQ) is in charge of the ASIC control and the administration of the whole readout process. Collected data is processed and sent to a computer trough Ethernet connection. Several MADDAQ boards can work in parallel independently or in coincidence mode. Measurements with the system are presented and characterization of the system is described.