Trigger performance evaluation and anti-coincidence demonstration of an event-driven SOI pixel detector for x-ray astronomy

We are developing x-ray Silicon-On-Insulator (SOI) pixel sensors, called "XRPIX" for the next generation x-ray astronomy satellites. The XRPIX has the unique function of event trigger and hit address outputs allowing us to read out signals only from the x-ray detected pixels. In order to use the XRPIX for the x-ray observatories, the sufficient time resolution is required to discriminate non x-ray events using the anti-coincidence method. For this method, a hit trigger of the XRPIX with a short delay and jitter time (~10μs) is required since the typical hitting rate of the high-energy background events on active shields is ~10kHz. Therefore, we have evaluated the trigger performance using the laser-generated pseudo-x-ray instead of x-ray sources. This allows us to easily control the timing, the position, and the energy of the hit events on the XRPIX. We estimated trigger's delay and jitter time to be ≲1μs. Here, we will report on the results of the trigger evaluation.