Results at 300 keV for both the modulation transfer function (MTF) and the detective quantum efficiency (DQE) are presented. These have different characteristics and so it is important to compare their imaging properties carefully with a view to optimise how each is used. There are currently three commercially available detectors of this type: the Direct Electron DE-20, the FEI Falcon II and the Gatan K2 Summit. Low dose electron imaging applications such as electron cryo-microscopy are now benefitting from the improved performance and flexibility of recently introduced electron imaging detectors in which electrons are directly incident on backthinned CMOS sensors. [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH (United Kingdom) [Crystallography and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E 7HX (United Kingdom) Henderson, R. [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH (United Kingdom) Clare, D. McMullan, G., E-mail: [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH (United Kingdom) Faruqi, A.R. These results highly recommend the replacement of current phosphor screen and charge coupled device imaging systems with such new directly exposed position sensitive electron detectors.Ĭomparison of optimal performance at 300 keV of three direct electron detectors for use in low dose electron microscopy Moldovan, G Li, X Kirkland, A, E-mail: new generation of imaging detectors is being considered for application in TEM, but which device architectures can provide the best images? Monte Carlo simulations of the electron-sensor interaction are used here to calculate the expected modulation transfer of monolithic active pixel sensors (MAPS), hybrid active pixel sensors (HAPS) and double sided Silicon strip detectors (DSSD), showing that ideal and nearly ideal transfer can be obtained using DSSD and MAPS sensors. A concentration of 3 at% nitrogen was detected with a total electron dose of only 1.7 e-/Ã…2, extending the boundaries of EELS signal detection at low electron doses.Ĭan direct electron detectors outperform phosphor-CCD systems for TEM? A change in the fine structure of nitrogen K and the carbon K edges were recorded during irradiation. We studied the oxygen K edge of amorphous ice and obtained a signal noise ratio up to 10 times higher than with a conventional CCD.We report the application of electron counting to record time-resolved EEL spectra of a biological protein embedded in amorphous ice, revealing chemical changes observed in situ while exposed by the electron beam. Here we report the use of an electron-counting direct-detection camera for EEL spectroscopy. In spectroscopy, in particular in combination with a monochromator, the signal can be extremely weak and the detection limit is principally defined by noise introduced by the detector.
With the recent development of electron-counting direct-detection cameras, micrographs can be acquired under very low electron doses at significantly improved signal-to-noise ratio. Since the development of parallel electron energy loss spectroscopy (EELS), charge-coupled devices (CCDs) have been the default detectors for EELS.
Low-dose electron energy-loss spectroscopy using electron counting direct detectors. The technical challenges associated with generating and processing large amounts of data are also discussed. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The detector has a 15-bit dynamic range, better than 30-μmμm spatial resolution and less than 20 analogue-to-digital converter count RMS pixel noise. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. Here we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. A direct electron detector for time-resolved MeV electron microscopyĮnergy Technology Data Exchange (ETDEWEB)
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