Paul Scherrer Institut

Bernd Schmitt

Roberto Dinapoli

Aldo Mozzanica

Anna Bergamaschi

Xintian Shi

Dominic Greiffenberg

Christian Broennimann

A system counts photon interactions in an array of photosensitive diodes and addresses the issue of improving position resolution. Every photo-detector diode of the array is connected to a readout unit cell containing a high-gain charge-to-voltage amplifier, a shaper, at least two comparators with independent thresholds and at least one interpixel communication logic, receiving as input signals from comparator outputs of the same readout unit cell and of the neighboring readout unit cells. This logic is then connected to at least one counter, each counter followed by a counter readout. By means of the digital interpixel communication logic and the set of comparators with different thresholds in every readout unit cell, it is possible to determine the photon hit position in the detector with a higher position resolution than the physical photo-detector size including the removal of the corner effect in pixel detectors.

Single photon counting detectors in strip or pixel design having digital inter-pixel communication logic comprising a physical area of each photo-detector diode being subdivided into a plurality of smaller sections representing a plurality of virtual channels

An X ray detector with single photon measurement capabilities includes a layer of photosensitive material and an N&#xd7;M array of photo-detector diodes in the layer of photosensitive material. The photo-detector diodes have a bias potential interface and a diode output interface. An N&#xd7;M array of high gain, low noise readout unit cells are assigned to the photo-detector diodes. Each readout unit cell has an input interface connecting the diode output interface to a high-gain charge-to-voltage amplifier with integration capacitors. The high-gain charge-to-voltage amplifier can switch between different gains. A comparator and a digital block monitors the charge of the integration capacitance and switches the gain depending from the monitored charge of the integration capacitance. The pixel detector provides the possibility of in pixel intermediate evaluation of an automatic gain switching circuit state to increase the dynamic range of the detector in case of quasi continuous incoming particle flux.

Method for extending the dynamic range of a pixel detector system using automatic gain switching

A single photon counting detector system has a layer of photosensitive material and an N&#xd7;M array of photo-detector diodes. Each photo-detector diode has a bias potential interface and a diode output interface. The bias potential interface is connected to bias potential. An N&#xd7;M array of high gain, low noise readout unit cells is provided, one readout unit cell for each photo-detector diode. Each readout unit cell has an input interface connected to the diode output interface, a high-gain voltage amplifier with an integration capacitor at least two parallel lines of digital counters, each having a comparator with an individually selectable threshold and a gateable section to determine the counting intervals of the digital counters. A multiplexer allows access to the readout cell unit either on a per pixel basis or for several pixels in parallel to read out the digital counter to a data processor transferring the data off chip.

Single photon counting detector system having improved counter architecture

An X-ray detector contains a layer of photosensitive material and an N&#xd7;M array of photo-detector diodes disposed in the photosensitive material. Each of the diodes has a bias potential interface and a diode output interface. The bias potential interface is connected to a bias potential. The X-ray detector further has an N&#xd7;M array of high gain, low noise readout unit cells, one readout unit cell for each diode. Each cell contains an input interface connected to the diode output interface, a high-gain voltage amplifying device having an integration capacitor, a first switch in parallel to the integration capacitor and a sample/hold capacitor disposed between a second switch and third switch. The sample/hold capacitor is connectable to the voltage amplifying device via the second switch and is connectable to a signal output line. A multiplexer contains a row select and a column select circuit allowing access to each readout cell unit.

X-ray detector with integrating readout chip for single photon resolution

A readout chip for single photon counting has a plurality of N individually working channels each assigned to a respective detector diode. Each channel has a counter designed as a binary counter having a length of M bits and a number of programmable bits. Further, the readout chip has a serial shift register or parallel data input register for entering values for the counter and the programmable bits, and a number of data output shift registers each having a number of K data outputs. Means are provided for selectively multiplexing each of the K data outputs onto a selectable bit of the data output shift register.

Readout chip with binary counter for fast single photon counting

The invention is directed to increasing the time resolution capabilities of a photon counting imaging device. This is achieved by a photon-counting imaging device for single x-ray counting, including: a layer of photosensitive material; an N&#xd7;M array of photodetector diodes arranged in the layer of the photosensitive material; an N&#xd7;M array of readout unit cells including an high gain, low noise amplifying elements, one readout unit cell for each photodetector diode; the readout unit cells being controlled by a data processing elements; each readout unit cell comprising an internal data processing elements allowing to assign an output signal representing an amplifyied signal of the electron hole pairs generated by an incident photon or a predetermined number of incident photons in the respective photodetector diode to a preselectable region of interest; and the assignment of the output signal is accompanied by a time stamp generated by a clock means.

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Lauchringen, Germany

Bernd Schmitt