Silicon pixel detectors for Synchrotron beam lines

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The project aims to build on existing work in the University of Glasgow and Diamond detector development group to investigate novel silicon pixel detector architectures applicable to use at the Diamond Synchrotron. The student will work in the Glasgow detector development group with Dr Richard Bates (head of 3D detector group in the RD50 collaboration) and Dr Andrew Blue (expert on APS sensor testing), and in the Diamond Detector group with Dr Nicola Tartoni (head of Diamond detector group) and Dr Julien Marchal (detector expert with particular responsibility for organising testbeam activities in this project). The supervising academic staff member will be Dr Chris Parkes (head of Glasgow RD50 activities). Two technologies will be investigated: 1) Small dimension hybrid pixel devices with reduced charge sharing for use on 10-20 KeV X-ray beam lines 2) Active pixel sensors for soft x-ray diffraction, and high energy beam line real-time applications. The student will primarily concentrate on detector testing and characterisation, both in the Glasgow laboratory and on Diamond beamlines. Device modeling will be performed to underpin the analysis of the results. The student will spend part of their time at the University of Glasgow and part at the Diamond Synchrotron, depending on the project needs. The student will undertake the relevant PhD training courses at the University of Glasgow. 1) Hybrid Pixel Devices Currently existing commercial hybrid pixel devices are based on 170x170 micron pixels (in the state-of-the-art Pilatus system used at Diamond). At Diamond the needs for smaller pixel size silicon sensors have been clearly identified. Both the University of Glasgow and Diamond are members of the Medipix collaboration which produces single photon counting 55x55 micron pixel readout front-end electronics. However, conventional small pixel planar devices suffer from charge sharing between pixels. This can be addressed through either the use of 3D sensors to limit charge sharing or in the electronic read-out chip (or both). 3D sensors: This work builds on the highly successful previous CASE studentship which resulted in the design, simulation and first production of a novel 3D detector architecture sensor and the first 3D detector for synchrotron applications. These tests have demonstrated significantly reduced charge sharing. 3D fabrication techniques (applied to either 3D detectors or planar detectors) can yield edgeless devices which allow tiling of devices over an area, of obvious application to imaging at Diamond, and will be considered in a future production. Read-out Chip: The Medipix3 readout chip will soon be available which will attempt to reduce charge sharing through the electronic circuitry. The charge sharing in a conventional (as well as 3D) device will be compared against Medipix2. 2) APS Development Active pixel sensors (APS) have the key advantage over CCD devices that are conventionally used in Synchrotron applications, which is that the APS in-pixel electronics is configurable for the required application. At Diamond this has potential applications on soft X-ray diffraction beamlines (I10, I06) and, coupled with a scintillator, on High Energy beamlines (I15 and I12). Large area devices suitable for Synchrotron applications are producible from APS technology, and APS sensors can be readout with a high frame rate The University of Glasgow group, as part of MI3, has developed a setup and techniques for the characterisation of APS sensors. In recent years this has been applied to the characterisation of 4 types of APS sensor with dimensions from 45 micron down to 6 micron. APS sensors suitable for application at Diamond are already extant and will be tested in the early part of this CASE studentship. This initial study is likely to result (with additional grant applications) in suggestions to produce large area low noise APS sensors ideally tailored to Diamond applications.