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Author(s)
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Koenig, Thomas (Forschungszentrum Karlsruhe, ANKA) ; Procz, Simon (Freiburg U.) ; Cecilia, Angelica (Forschungszentrum Karlsruhe, ANKA) ; Ballabriga, Rafael (CERN) ; Baumbach, Tilo (Forschungszentrum Karlsruhe, ANKA) ; Llopart, Xavier (CERN) ; Fiederle, Michael (Freiburg U.) ; Zuber, Marcus (Forschungszentrum Karlsruhe, ANKA) ; Hamann, Elias (Forschungszentrum Karlsruhe, ANKA) ; Fauler, Alex (Freiburg U.) ; Campbell, Michael (CERN) |
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Abstract
| The spectroscopic performance of photon counting detectors is limited by the effects of charge sharing between neighboring pixels and the emission of characteristic X-rays. For these reasons, an event can be either missed or counted more than once. These effects become more and more of a concern when pixel pitches are reduced, and for the technology available so far, this meant that there would always be a trade-off between a high spatial and a high spectral resolution. In this work, we present first measurements obtained with the new Medipix3RX ASIC, which features a network of charge summing circuits establishing a communication between pixels which helps to mitigate these effects. Combined with cadmium telluride sensors, we show that this new technology is successful at improving a detector's spectroscopic capabilities even at pixel pitches as small as 55 mu m. At this pitch, we measure an energy response function similar to that observed for a pixel pitch of 165 mu m in the absence of a charge summing circuitry. This amounts to an effective reduction of the pixel area by at least one order of magnitude at a comparable energy response. Additionally, we present synchrotron measurements at high X-ray fluxes, where significant pulse pile-up occurs, and provide first experimental evidence for a net benefit when balancing spectroscopic performance and high flux tolerance in charge summing mode. |