Comparison of a CCD and an APS for soft x-ray diffraction

Stewart, G., Bates, R., Blue, A. , Clark, A., Dhesi, S.S., Maneuski, D., Marchal, J., Steadman, P., Tartoni, N. and Turchetta, R. (2011) Comparison of a CCD and an APS for soft x-ray diffraction. Journal of Instrumentation, 6(12), C12062. (doi: 10.1088/1748-0221/6/12/C12062)

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We compare a new CMOS Active Pixel Sensor (APS) to a Princeton Instruments PIXIS-XO: 2048B Charge Coupled Device (CCD) with soft X-rays tested in a synchrotron beam line at the Diamond Light Source (DLS). Despite CCDs being established in the field of scientific imaging, APS are an innovative technology that offers advantages over CCDs. These include faster readout, higher operational temperature, in-pixel electronics for advanced image processing and reduced manufacturing cost. The APS employed was the Vanilla sensor designed by the MI3 collaboration and funded by an RCUK Basic technology grant. This sensor has 520 x 520 square pixels, of size 25 μm on each side. The sensor can operate at a full frame readout of up to 20 Hz. The sensor had been back-thinned, to the epitaxial layer. This was the first time that a back-thinned APS had been demonstrated at a beam line at DLS. In the synchrotron experiment soft X-rays with an energy of approximately 708 eV were used to produce a diffraction pattern from a permalloy sample. The pattern was imaged at a range of integration times with both sensors. The CCD had to be operated at a temperature of -55°C whereas the Vanilla was operated over a temperature range from 20°C to -10°C. We show that the APS detector can operate with frame rates up to two hundred times faster than the CCD, without excessive degradation of image quality. The signal to noise of the APS is shown to be the same as that of the CCD at identical integration times and the response is shown to be linear, with no charge blooming effects. The experiment has allowed a direct comparison of back thinned APS and CCDs in a real soft x-ray synchrotron experiment.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Maneuski, Dr Dima and Blue, Dr Andrew and Bates, Dr Richard and Stewart, Dr Graeme
Authors: Stewart, G., Bates, R., Blue, A., Clark, A., Dhesi, S.S., Maneuski, D., Marchal, J., Steadman, P., Tartoni, N., and Turchetta, R.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Journal of Instrumentation
Publisher:Institute of Physics Publishing Ltd.
Copyright Holders:Copyright © 2011 IOP Publishing Ltd and SISSA
First Published:First published in Journal of Instrumentation 6(12):C12062
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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