A new silicon detector system for optical and low light imaging, based on DEPFET RNDR

We present a new CCD detector system for single optical photon and low light sources imaging. PnCCDs produced in the double sided silicon technology of the Max-Planck-Institut Halbleiterlabor have been operating for long in the field of X-ray imaging and have shown outstanding performance with respect to quantum efficiency, charge transfer efficiency, speed and spectroscopic resolution. With an anti-reflecting coating deposited on the ultra-thin and homogeneous photon entrance window it is possible to achieve a quantum efficiency close to 100% for near infrared and optical photons. However the electronics noise of 2 electrons r.m.s. obtained so far with X-ray pnCCD would hardly allow to detect signals generated by less than 10 optical photons. So, in order to perform single optical photon counting, a RNDR-DEFET amplifier has been implemented in the anode region of each pnCDD channel. This device allows measuring the signal charge coming from the pnCCD detector non destructively and arbitrary often. It has already theoretically and experimentally verified that this procedure makes it possible to reduce the readout noise down to a value below 0.3 electrons r.m.s. In order to readout a complete pnCCD a low noise multichannel readout time-variant shaping amplifier is mandatory. First results obtained coupling a RNDR device together with a custom designed ASIC implementing a trapezoidal weighting function will be presented. They show a readout noise of 0.25 electrons r.m.s. operating the pixel at -50degC.