Front-end electronics and data acquisition system for the MIDAS experiment

The MIDAS (MIcrowave Detection of Air Showers) experiment, a prototype detector to characterize the microwave emission of air showers induced by high energy cosmic rays, has been recently commissioned at the University of Chicago. The receivers, 53 feed horns in the 4GHz band, send the signal to fast power detectors which have logarithmic response to the input RF power. The integrated output signal is continuously digitized in custom 14-bit 20 MHz ADC modules. Data are then processed locally with on-board Field Programmable Gate Arrays (FPGAs) where the trigger logic allows discrimination of events. Local trigger pulses are sent out to a Master Board where a system-wise trigger pulse is generated and sent back to the ADC Modules. After each trigger, a 100 us time stream of data is packed and buffered for readout via the VME back plane. A VME GPS module is also used for precise timing information. Design, specifications of the electronic components, a description of the implemented trigger logic, and preliminary test results will be presented in this contribution.