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CCD Detectors in High- Resolution Biology Jian Guan 6-28-2013

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Overview Some Chemistry Concepts What is CCD? How does CCD work? Structure of CCD Principle of CCD Operation Pixel Size calculation

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1.12ev 3.55ev Some Chemistry Concepts

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Silicon Crystal

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What is CCD? Willard.S Boyle George Elwood Smith

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How does CCD work?

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Structure of CCD

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Principles of CCD Operation More than enough Damage Interference from X-ray

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Indirect Detection is much more acceptable: Electron energy conversion into light high conversion efficiency into visible radiation, reasonably short and well-defined decay time of the emitted scintillation, phosphor output wavelength matched to CCD sensitivity (which has a maximum at ~700 nm), resistance to radiation damage, a convenient, reproducible method of depositing a thin layer of phosphor on a flat surface. P20: zinc cadmium sulphide doped with silver P43: gadolinium oxy-sulphide doped with terbium

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Optical coupling: Lens or Fibre optics Lens couplingFibre optics

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Readout and analog-to-digital

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Noises Dark current noise Readout noise Spurious events due to X-rays or cosmic rays Temperature-dependent keep cold Faster readout, more than one read out node Software algorithm

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Electron diffraction applications

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Pixel Size Calculation Calculation of Pixel Size from a CCD Image Pixel size = Actual pixel size Magnification Save CCD image in DM3 file format Get the pixel size information from the Digital Micrograph program If not:

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Apogee AP7p CCD Pixel Array: 512 x 512 pixels Array Dimensions: 12.3 mm x 12.3 mm Pixel Dimensions: 24 micron square Actual pixel size = Array dimension Pixel arry = 12.3/512 = 24 micron = 240,000 Angstrom Magnification = 100,000 Pixel size = Actual pixel size Magnification = 2.4 Angstrom

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