961 research outputs found

    A position- and time-sensitive photon-counting detector with delay-line read-out

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    We have developed image intensifier tubes with delay-anode read-out for time- and position-sensitive photon counting. The timing precision is better than 1 ns with 1000x1000 pixels position resolution and up to one megacounts/s processing rate. Large format detectors of 40 and 75 mm active diameter with internal helical-wire delay-line anodes have been produced and specified. A different type of 40 and 25 mm tubes with semi-conducting screen for image charge read-out allow for an economic and robust tube design and for placing the read-out anodes outside the sealed housing. Two types of external delay-line anodes, i.e. pick-up electrodes for the image charge, have been tested. We present tests of the detector and anode performance. Due to the low background this technique is well suited for applications with very low light intensity and especially if a precise time tagging for each photon is required. As an example we present the application of scintillator read-out in time-of-flight (TOF) neutron radiography. Further applications so far are Fluorescence Life-time Microscopy (FLIM) and AstronomyComment: Proceedings of SPIE Conference "Optics and Optoelectronics", 16 - 19. Apr.200

    Responding to, and learning from, peer review feedback.

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    What is peer review in research? Peer review is the process of assessing the scientific quality of a research proposal, research report and/or paper by an independent expert, usually an academic or clinical expert

    Femscan -The development of the image dissector to a tube with femtosecond time resolution

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    ABSTRACT The Image Dissector was one of the firsts all electronic TV tubes and was described by Farnsworth in 1934. (Ref 1). Fifty years later, in 1983, more modern image dissectors were used to measure the electron bunch lengths in synchrotrons. The advent of modern computers and high-speed electronics enables these rather elderly tubes to be used in exciting new applications. This paper described how we have adapted the image dissector to enable the development of low cost instruments with exceptional bandwidth, sensitivity and sampling rate for optical signals

    Bias-Dependent Generation and Quenching of Defects in Pentacene

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    We describe a defect in pentacene single crystals that is created by bias stress and persists at room temperature for an hour in the dark but only seconds with 420nm illumination. The defect gives rise to a hole trap at Ev + 0.38eV and causes metastable transport effects at room temperature. Creation and decay rates of the hole trap have a 0.67eV activation energy with a small (108 s-1) prefactor, suggesting that atomic motion plays a key role in the generation and quenching process.Comment: 10 pages, 3 figure

    Time and position sensitive single photon detector for scintillator read-out

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    We have developed a photon counting detector system for combined neutron and gamma radiography which can determine position, time and intensity of a secondary photon flash created by a high-energy particle or photon within a scintillator screen. The system is based on a micro-channel plate photomultiplier concept utilizing image charge coupling to a position- and time-sensitive read-out anode placed outside the vacuum tube in air, aided by a standard photomultiplier and very fast pulse-height analyzing electronics. Due to the low dead time of all system components it can cope with the high throughput demands of a proposed combined fast neutron and dual discrete energy gamma radiography method (FNDDER). We show tests with different types of delay-line read-out anodes and present a novel pulse-height-to-time converter circuit with its potential to discriminate gamma energies for the projected FNDDER devices for an automated cargo container inspection system (ACCIS).Comment: Proceedings of FNDA 201

    New technologies of representation, collaborative autoethnographies and ‘taking it public’: An example from ‘Facilitating Communication on Sexual Topics in Education’

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    New technologies for representing and communicating autoethnographies make it possible to be publically visible in new and interesting ways that weren’t possible prior to the digital revolution. An important ingredient in this process is the internet platforms that can make the digitisation of performances accessible across the world, even for short, modest creations from less experienced digital storytellers and film makers. As an illustration of the potential applications of digital technologies for ‘taking’ autoethnographic research to the ‘public,’ and making our research accessible to a wider audience we share ‘Reverberations,’ a collaborative autoethnography exploring bullying, homophobia, and other types of sexual harassment and associated feelings of shame, embarrassment and fear which often surround these topics

    National Mesothelioma Virtual Bank: A standard based biospecimen and clinical data resource to enhance translational research

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    Background: Advances in translational research have led to the need for well characterized biospecimens for research. The National Mesothelioma Virtual Bank is an initiative which collects annotated datasets relevant to human mesothelioma to develop an enterprising biospecimen resource to fulfill researchers' need. Methods: The National Mesothelioma Virtual Bank architecture is based on three major components: (a) common data elements (based on College of American Pathologists protocol and National North American Association of Central Cancer Registries standards), (b) clinical and epidemiologic data annotation, and (c) data query tools. These tools work interoperably to standardize the entire process of annotation. The National Mesothelioma Virtual Bank tool is based upon the caTISSUE Clinical Annotation Engine, developed by the University of Pittsburgh in cooperation with the Cancer Biomedical Informatics Grid™ (caBIG™, see http://cabig.nci.nih.gov). This application provides a web-based system for annotating, importing and searching mesothelioma cases. The underlying information model is constructed utilizing Unified Modeling Language class diagrams, hierarchical relationships and Enterprise Architect software. Result: The database provides researchers real-time access to richly annotated specimens and integral information related to mesothelioma. The data disclosed is tightly regulated depending upon users' authorization and depending on the participating institute that is amenable to the local Institutional Review Board and regulation committee reviews. Conclusion: The National Mesothelioma Virtual Bank currently has over 600 annotated cases available for researchers that include paraffin embedded tissues, tissue microarrays, serum and genomic DNA. The National Mesothelioma Virtual Bank is a virtual biospecimen registry with robust translational biomedical informatics support to facilitate basic science, clinical, and translational research. Furthermore, it protects patient privacy by disclosing only de-identified datasets to assure that biospecimens can be made accessible to researchers. © 2008 Amin et al; licensee BioMed Central Ltd
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