Modelling electron distributions within ESA's Gaia satellite CCD pixels to mitigate radiation damage - Astrophysics > Instrumentation and Methods for AstrophysicsReport as inadecuate




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Abstract: The Gaia satellite is a high-precision astrometry, photometry andspectroscopic ESA cornerstone mission, currently scheduled for launch in 2012.Its primary science drivers are the composition, formation and evolution of theGalaxy. Gaia will achieve its unprecedented positional accuracy requirementswith detailed calibration and correction for radiation damage. At L2, protonscause displacement damage in the silicon of CCDs. The resulting traps captureand emit electrons from passing charge packets in the CCD pixel, distorting theimage PSF and biasing its centroid. Microscopic models of Gaia-s CCDs are beingdeveloped to simulate this effect. The key to calculating the probability of anelectron being captured by a trap is the 3D electron density within each CCDpixel. However, this has not been physically modelled for the Gaia CCD pixels.In Seabroke, Holland and Cropper 2008, the first paper of this series, wemotivated the need for such specialised 3D device modelling and outlined howits future results will fit into Gaia-s overall radiation calibration strategy.In this paper, the second of the series, we present our first results usingSilvaco-s physics-based, engineering software: the ATLAS device simulationframework. Inputting a doping profile, pixel geometry and materials into ATLASand comparing the results to other simulations reveals that ATLAS has a freeparameter, fixed oxide charge, that needs to be calibrated. ATLAS issuccessfully benchmarked against other simulations and measurements of a testdevice, identifying how to use it to model Gaia pixels and highlighting theeffect of different doping approximations.



Author: G. M. Seabroke 1, A. D. Holland 1, D. Burt 2, M. S. Robbins 2 1 Planetary and Space Sciences Research Institute, The Open Univers

Source: https://arxiv.org/







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