Home About us Contact
|
Home About us Contact | ||
|
|
||
Pixel Detector (pixel + detector)
Selected AbstractsCharge-injection photogate pixel fabricated in CMOS silicon-on-insulator technologyINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 2 2009Daniel Durini Abstract Concept, theoretical analysis, and experimental results obtained from a charge-injection photogate (CI-PG) pixel detector fabricated in CMOS silicon-on-insulator (SOI) technology are presented. The charge collected in the photodetector during a certain charge collection (integration) time is injected into the substrate for readout. This readout principle presents a huge internal photocurrent amplification (,104) taking place in the photodetector, obtained through the ,time-compression' approach. Here, the readout circuitry is fabricated on highly doped, 200,nm thick, SOI film, while the photogate detector is fabricated on higher resistivity handle-wafer. The latter, together with the 30,V biasing possibilities, enhances the quantum efficiency of the pixel, especially for irradiations with wavelengths in the near-infra-red part of the spectra. Copyright © 2008 John Wiley & Sons, Ltd. [source] High-resolution three-dimensional reciprocal-space mapping of InAs nanowiresJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2009S. O. Mariager Grazing-incidence X-ray diffraction is combined with a two-dimensional pixel detector to obtain three-dimensional reciprocal-space maps of InAs nanowires grown by molecular beam epitaxy. This rapid data-acquisition technique and the necessary correction factors are described in general terms, as well as for the specific setup used, for which a resolution of ,2 × 10,3,Å is computed. The three-dimensional data sets are obtained by calculating the reciprocal space coordinates for every pixel in the detected images, and are used to map the diffuse scattering from the nanowires as both two-dimensional reciprocal-space maps and three-dimensional isosurfaces. The InAs nanowires are shown to consist mainly of wurtzite crystal with a c/a ratio of 1.641. The diffuse scattering reveals two different facet structures, both resulting in hexagonal cross sections of the nanowires. [source] Reciprocal-space imaging of a real quasicrystal.JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2008A feasibility study with PILATUS 6M How many of the theoretically densely distributed Bragg reflections of a quasicrystal can be observed employing an area detector and synchrotron radiation? How does the reflection density of a real quasicrystal change as a function of exposure time, and what is the minimum distance between reflections? What does the distribution of diffuse scattering look like? To answer these questions, the Bragg reflection density of a perfect icosahedral quasicrystal with composition Al64Cu23Fe13 was measured employing a novel type of single-photon-counting X-ray pixel detector, PILATUS 6M, which allows noise-free data collection with the extraordinarily large dynamic range of 20,bit. The reflection density was found to be two orders of magnitude lower than expected for a strictly quasiperiodic structure. Moreover, diffuse scattering reflects significant structural disorder, breaking six-dimensional F -lattice symmetry. These findings have some implications for the interpretation of physical properties. [source] Silicon drift and pixel devices for X-ray imaging and spectroscopyJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2006G. Lutz Starting from the basic photon detection process in semiconductors, the function, principles and properties of sophisticated silicon detectors are discussed. These detectors are based on, or inspired by, the semiconductor drift detector. They have already shown their potential in X-ray astronomy (pn-CCD) and in X-ray spectroscopy (silicon drift diode), and further detector types (DEPFET pixel detector and macro-pixel detector) are under development for several other future experiments. The detectors seem to be very well suited for synchrotron radiation experiments. [source] A novel epitaxially grown LSO-based thin-film scintillator for micro-imaging using hard synchrotron radiationJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2010Paul-Antoine Douissard The efficiency of high-resolution pixel detectors for hard X-rays is nowadays one of the major criteria which drives the feasibility of imaging experiments and in general the performance of an experimental station for synchrotron-based microtomography and radiography. Here the luminescent screen used for the indirect detection is focused on in order to increase the detective quantum efficiency: a novel scintillator based on doped Lu2SiO5 (LSO), epitaxially grown as thin film via the liquid phase epitaxy technique. It is shown that, by using adapted growth and doping parameters as well as a dedicated substrate, the scintillation behaviour of a LSO-based thin crystal together with the high stopping power of the material allows for high-performance indirect X-ray detection. In detail, the conversion efficiency, the radioluminescence spectra, the optical absorption spectra under UV/visible-light and the afterglow are investigated. A set-up to study the effect of the thin-film scintillator's temperature on its conversion efficiency is described as well. It delivers knowledge which is important when working with higher photon flux densities and the corresponding high heat load on the material. Additionally, X-ray imaging systems based on different diffraction-limited visible-light optics and CCD cameras using among others LSO-based thin film are compared. Finally, the performance of the LSO thin film is illustrated by imaging a honey bee leg, demonstrating the value of efficient high-resolution computed tomography for life sciences. [source] | ||||||||||