Gated mode operation of DEPFET sensors for the Belle II pixel detector

The DEPFET collaboration develops highly granular, ultra-transparent active pixel detectors for high-performance vertex reconstruction at the Belle II experiment, KEK, Japan. The key features of the sensors have been proven: integration of the first amplification stage into the sensor, very low sensor thickness, high signal-to-noise ratio, non-destructive pulse-height readout, and the connection to readout ASICs with sufficient speed. A complete detector concept has been developed, including solutions for mechanical support, cooling and services. During the beam injection, the sensors will be flooded with meaningless particle hits which have to be ignored. To do so, the sensors will be switched to the so-called “gated mode”. This is a kind of electronic shutter in which the signals of previous particles are preserved, and the signals of upcoming background particles are cleared right away. After a brief introduction to the Belle II experiment, the Pixel Detector PXD and the DEPFET sensor concept, this contribution will focus on the first measurement results of the gated mode on a small sensor with the prototype DEPFET technology. It will discuss the underlying principle, the laboratory setup, and the results of laser tests using the (close to) final readout ASICs and procedures as similar to the real experiment as possible.