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The use of CCDs and EM-CCDs for future soft x-ray spectrometers

Tutt, James H.; Holland, Andrew D.; Murray, Neil J.; Hall, David J.; Endicott, James and McEntaffer, Randall L. (2012). The use of CCDs and EM-CCDs for future soft x-ray spectrometers. In: Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, 1-6 July 2012, Amsterdam.

URL: http://proceedings.spiedigitallibrary.org/proceedi...
DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1117/12.925138
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Abstract

CCDs have been used on several successful X-ray space missions including high resolution soft X-ray spectrometers, such as the Reflection Grating Spectrometer on XMM-Newton1 and the LETG and HETG on Chandra2. These instruments had a resolving power of ( E / Δ E) ~300; however, with new technology this can be improved allowing resolution to the thermal limit. In the soft X-ray band (200 eV to 10 keV) a resolution of around 3000 is required resolve all of the possible absorption and emission features. Through the development of instruments for the OP-XGS on IXO3 and the WHIMEx explorer mission4 it has been shown that an instrument capable of this resolution on a spacecraft is possible. CCDs are the ideal detector for use in detection of X-rays at this energy as they provide positional information allowing a high level of spatial resolution and their inherent energy resolution allowing diffracted orders to be separated. This paper will investigate the use of CCDs and possible use of EM-CCDs in soft X-ray spectroscopy. The multiplication of signal in the charge domain can increase the detectability of low energy photons, improving the Signal-to-Noise Ratio. Multiplication gain has been shown to degrade the resolution of a device as described by the Modified Fano Factor5, so this has to be taken into account in instrument design when overlapping spectral orders are needed to achieved the necessary resolution. The use of optical filters on the CCDs and their effect on quantum efficiency at soft X-ray energies is discussed together with possible improvements to existing technology.

Item Type: Conference Item
Copyright Holders: 2012 Society of Photo-Optical Instrumentation Engineers (SPIE)
Extra Information: Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray
Amsterdam, Netherlands, July 01, 2012
SPIE Proceedings, Volume 8443. Detector Technology for Future Missions
Keywords: absorption; charge-coupled devices; equipment and services; optical filters; photons; quantum efficiency; reflection; sensors; signal to noise ratio; spectrometers
Academic Unit/Department: Science > Physical Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 34703
Depositing User: Jason Gow
Date Deposited: 19 Oct 2012 09:49
Last Modified: 14 Nov 2012 12:01
URI: http://oro.open.ac.uk/id/eprint/34703
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