CIX - A Detector for Spectral Enhanced X-ray Imaging by Simultaneous Counting and Integrating

A hybrid pixel detector based on the concept of simultaneous charge integration and photon counting will be presented. The second generation of a counting and integrating X-ray prototype CMOS chip (CIX) has been operated with different direct converting sensor materials (CdZnTe and CdTe) bump bonded to its 8x8 pixel matrix. Photon counting devices give excellent results for low to medium X-ray fluxes but saturate at high rates while charge integration allows the detection of very high fluxes but is limited at low rates by the finite signal to noise ratio. The combination of both signal processing concepts therefore extends the resolvable dynamic range of the X-ray detector. In addition, for a large region of the dynamic range, where counter and integrator operate simultaneously, the mean energy of the detected X-ray spectrum can be calculated. This spectral information can be used to enhance the contrast of the X-ray image. The advantages of the counting and integrating signal processing concept and the performance of the imaging system will be reviewed. The properties of the system with respect to dynamic range and sensor response will be discussed and examples of imaging with additional spectral information will be presented.Comment: 12 pages, 14 figures, SPIE Medical Imaging Conference, San Diego, 200

Development of a hard X-ray split-and-delay line and performance simulations for two-color pump-probe experiments at the European XFEL

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Review of Scientific Instruments 89, 063121 (2018) and may be found at https://doi.org/10.1063/1.5027071.A hard X-ray Split-and-Delay Line (SDL) under construction for the Materials Imaging and Dynamics station at the European X-Ray Free-Electron Laser (XFEL) is presented. This device aims at providing pairs of X-ray pulses with a variable time delay ranging from −10 ps to 800 ps in a photon energy range from 5 to 10 keV for photon correlation and X-ray pump-probe experiments. A custom designed mechanical motion system including active feedback control ensures that the high demands for stability and accuracy can be met and the design goals achieved. Using special radiation configurations of the European XFEL’s SASE-2 undulator (SASE: Self-Amplified Spontaneous Emission), two-color hard x-ray pump-probe schemes with varying photon energy separations have been proposed. Simulations indicate that more than 109 photons on the sample per pulse-pair and up to about 10% photon energy separation can be achieved in the hard X-ray region using the SDL.BMBF, 05K13KT4, Verbundprojekt FSP 302 - Freie-Elektronen-Laser: Nanoskopische Systeme. Teilprojekt 1: Split-and-Delay Instrument für die European XFEL Beamline Materials Imaging and DynamicsBMBF, 05K16BC1, Split-and-Delay Instrument für die European XFEL Beamline Materials Imaging and Dynamic

Real-time in-vivo μ-imaging with Medipix2

Abstract An X-ray micro-radiographic system based on the Medipix2 semiconductor pixel detector for dynamic high spatial resolution and for high contrast imaging has been developed. Our system is based on a micro-focus and nano-focus X-ray tube and the hybrid single-photon counting silicon pixel detector Medipix2 (matrix 256×256 sq. pixels of 55 μm pitch). This compact table-top system stands promising as a new tool in the field of small animal imaging as well as in the in-vivo observation of dynamic processes inside living organisms. The main advantages of these Medipix2 pixel detectors include: high sensitivity to low-energy X-ray photons; position sensitive and noiseless single-photon detection with preselected photon energies; single-quantum counting in each pixel performed by digital counter (therefore there is no dark current); digital integration (providing unlimited dynamic range and absolute linearity in device response to number of photons, high sensitivity and high contrast); real-time digital information, high-speed digital communication and data transfer. We improve the picture quality with the help of statistical data analysis and extended the calibration of individual pixels response. 2D and 3D radiographic images of samples demonstrate the potential and applicability of our system for precise in-vivo X-ray high-resolution dynamic diagnostic and biological studies. Obtained results are shown on small animal and organic samples

The European Photon Imaging Camera on XMM-Newton: The MOS Cameras

The EPIC focal plane imaging spectrometers on XMM-Newton use CCDs to record the images and spectra of celestial X-ray sources focused by the three X-ray mirrors. There is one camera at the focus of each mirror; two of the cameras contain seven MOS CCDs, while the third uses twelve PN CCDs, defining a circular field of view of 30 arcmin diameter in each case. The CCDs were specially developed for EPIC, and combine high quality imaging with spectral resolution close to the Fano limit. A filter wheel carrying three kinds of X-ray transparent light blocking filter, a fully closed, and a fully open position, is fitted to each EPIC instrument. The CCDs are cooled passively and are under full closed loop thermal control. A radio-active source is fitted for internal calibration. Data are processed on-board to save telemetry by removing cosmic ray tracks, and generating X-ray event files; a variety of different instrument modes are available to increase the dynamic range of the instrument and to enable fast timing. The instruments were calibrated using laboratory X-ray beams, and synchrotron generated monochromatic X-ray beams before launch; in-orbit calibration makes use of a variety of celestial X-ray targets. The current calibration is better than 10% over the entire energy range of 0.2 to 10 keV. All three instruments survived launch and are performing nominally in orbit. In particular full field-of-view coverage is available, all electronic modes work, and the energy resolution is close to pre-launch values. Radiation damage is well within pre-launch predictions and does not yet impact on the energy resolution. The scientific results from EPIC amply fulfil pre-launch expectations.Comment: 9 pages, 11 figures, accepted for publication in the A&A Special Issue on XMM-Newto

透過X線撮影におけるFCRとフィルムの濃度特性の比較

Fuji Computed Radiography（FCR）uses Imaging Plate（IP）instead of a film for radiography．IP is read as a digital imaging data by a laser scanner and can be processed by imaging technique．Since IP has a large dynamic range compared with a film，it is possible to take a picture of a subject with composite structure having both low density and high density in one irradiation of X-ray．However，if we are to decipher the picture of FCR on the basis of a film，we have to understand the characteristic of FCR．In this study the characteristic curve of FCR and X-ray film is compared．When only low irradiation voltage gives good contrast to an X-ray film，high irradiation voltage can also give good contrast to FCR image by using a short irradiation．This result shows that high irradiation voltage with short irradiation time should be used when the suitable X-ray energy to a subject cannot be decided beforehand

Design of pixel-level ADCs for energy-sensitive hybrid pixel detectors

Single-photon counting hybrid pixel detectors have shown\ud to be a valid alternative to other types of X-ray imaging\ud devices due to their high sensitivity, low noise, linear behavior\ud and wide dynamic range. One important advantage of these\ud devices is the fact that detector and readout electronics are\ud manufactured separately. This allows the use of industrial\ud state-of-the-art CMOS processes to make the readout\ud electronics, combined with a free choice of detector material\ud (high resistivity Silicon, GaAs or other). By measuring not\ud only the number of X-ray photons but also their energies (or\ud wavelengths), the information content of the image increases,\ud given the same X-ray dose. We have studied several\ud possibilities of adding energy sensitivity to the single photon\ud counting capability of hybrid pixel detectors, by means of\ud pixel-level analog-to-digital converters. We show the results of\ud simulating different kinds of analog-to-digital converters in\ud terms of power, area and speed