Developing a high-resolution x-ray imager using electron-multiplying (EM) CCDs

Abstract

Applications at synchrotron facilities such as macromolecular crystallography and high energy X-ray diffraction require high resolution imaging detectors with high dynamic range and large surface area. Current systems can be split into two main categories: hybrid pixel detectors and scintillator-coupled Charge-Coupled Devices (CCDs). Whilst both have limitations, CCD-based systems (coupled to fibre-optics to increase imaging area) are often used in these applications due to their small pixels and the high resolution. Electron-Multiplication CCDs (EM-CCDs) are able to suppress the readout noise associated with increased readout speed offering a low noise, high speed detector solution. A previous pilot study using a small-area (8 mm × 8 mm) scintillator-coupled EM-CCD found that through high frame-rates, low noise and novel uses of photon-counting, resolution could be improved from over 80 µm to 25 µm at 2 fps. To further improve this detector system, high speed readout electronics can be used alongside a fibre-optic taper and EM-CCD to create a "best of both worlds" solution consisting of the high resolution of a CCD, along with the low noise, high speed (high dynamic range) and large effective area of pixel detectors. This paper details the developments in the study and discusses the latest results and their implication on the system design.

Transnational aging among older Turkish and Moroccan migrants in the Netherlands: Determinants of transnational behavior and transnational belonging

“…The constant confrontation between a simultaneous home "here" and home "there" (Zontini, 2015) on an emotional and imagined level is a marker of transnational belonging. This could be particularly prominent for older migrants under study here, as they spent a substantial part of their youths in the country of origin, and, in addition, it was found that people tend to reminisce about the past more in older age (Cohen & Taylor, 1998).…”

“…This may be explained explicitly by the aging component in transnational aging. As people become older and health deteriorates, not only do they reminisce about lost times and places, but they also contemplate more on where to die (Becker, 2002;Cohen & Taylor, 1998).…”

“…Yet, our focus was not on studying how aging impacts transnational orientation, but how transnational engagements come about in old age and how these can be understood. Throughout the paper we make clear why certain transnational involvements are potentially salient when being older, of which considering return migration (Hunter, 2011) is the most obvious, but we also discuss how visiting the country of origin and emotional attachment to it are of importance in older age (Cohen & Taylor, 1998;Fokkema et al, 2016). Furthermore, we study specific features of old age that could impact transnational aging, like poor health.…”

High-resolution soft x-ray spectrometry using the electron-multiplying charge-coupled device (EM-CCD)

“…In this study we have taken the example of SAXES at the Swiss Light Source, PSI, in which the EM-CCD has been shown to provide the ideal detector for consideration in any future spectrometer upgrade. The use of the EM-CCD is of course not limited to soft X-ray detection and developments for hard X-ray detection using scintillator-coupled EM-CCDs for synchrotron research are ongoing [10][11][12][13][14]23 .…”

Development of EM‐CCD‐based X‐ray detector for synchrotron applications

“…The ElectronMultiplying (EM) CCD was designed for low light level imaging such as night-time surveillance and differs from the standard CCD through the addition of a "gain register" [3]. By multiplying the signal by thousands, the effective read noise of the device can be dramatically reduced, allowing operation at very high speeds with sub-electron read noise, offering high resolution centroiding and energy discrimination [4] [5].As part of an STFC-funded IPS grant in collaboration with e2v technologies, we have developed a high-speed (24 fps full-frame), large area X-ray detector module, using high-speed electronics provided by XCAM ltd [6]. This project aims to transfer this technology and expertise to applications in synchrotron research through the use of a proof-of-concept camera module.…”