A DECTRIS hybrid pixel detector is composed of a silicon sensor, which is a two-dimensional array of p-n diodes processed in high-resistivity silicon, connected to an array of readout channels designed with advanced CMOS technology. Each readout channel is connected to its corresponding detecting element through a microscopic indium sphere, with a typical diameter of 18 μm. This process is called microbump-bonding and was refined at the Paul Scherrer Institut. In the Pilatus detector, the hybrid pixel features single-photon counting using a preamplifier, which amplifies the charge generated in the sensor by the incoming X-ray, and a discriminator, which produces a count if the incoming charge exceeds a predefined threshold. The discriminator feeds a 20-bit counter, which leads to a digital storage unit and noiseless readout of the number of detected X-rays per pixel.
Features • Direct detection of X-rays in single photon counting mode • Excellent signal-to-noise ratio: No dark current or readout noise • Radiation tolerant design • High dynamic range: 1:1,048,576 photons per pixel • High counting rates: up to 2 × 106 photons per second • Short readout time: less than 3 ms • High framing rates of over 200 images per second • Excellent point-spread function • Adjustable threshold to suppress fluorescence • Electronically gateable