S-Band cavity BPM readout electronics for the ELI-NP gamma beam source

The Extreme Light Infrastructure – Nuclear Physics Gamma Beam Source (ELI-NP GBS) facility will provide an high intensity laser and a very intense gamma beam for various experiments. The gamma beam is generated through incoherent Compton back-scattering of a laser light off a high brightness electron beam provided by a 720MeV warm LINAC. The electrons are organized in compact trains with up to 32 bunches, each separated by 16ns. To optimize the laser-electron interaction and therefore the generation of the gamma rays, one big challenge is to precisely monitor the trajectory of each electron bunch. To match this requirement, at the interaction point two S-band cavity beam position monitors will be used, and the related readout system should perform bunch-bybunch position measurements with sub-μm resolution. Using 500MS/s ADC converters and dedicated data processing, the readout system proposes an alternative measurement concept. In this paper the architecture of the system, the implemented signal processing and the results of the first laboratory tests will be presented.