Large aperture CCD x ray detector for protein crystallography using a fiberoptic taper
Abstract
A detector with a 114 mm aperture, based on a charge-coupled device (CCD), has been designed for x-ray diffraction studies in protein crystallography. The detector was tested on a beamline of the National Synchrotron Light Source at Brookhaven National Laboratory with a beam intensity greater than 10(exp 9) x-ray photons/s. A fiberoptic taper, an image intensifier and a lens demagnify, intensify, and focus the image onto a CCD having 512 x 512 pixels. A detective quantum efficiency (DOE) of 0.36 was obtained by evaluating the statistical uncertainty in the detector output. The dynamic range of a 4 x 4 pixel resolution element, comparable in size to a diffraction peak, was 10(exp 4). The point-spread function shows FWHM resolution of approximately 1 pixel, where a pixel on the detector face is 160 microns. A complete data set, consisting of forty-five 1 deg rotation frames, was obtained in just 36 s of x-ray exposure to a crystal of chicken egg-white lysozyme. In a separate experiment, a lysozyme data set consisting of 495 0.1 deg frames, was processed by the MADNES data reduction program, yielding symmetry R-factors for the data of 3.2 to 3.5 percent. Diffraction images from crystals of the myosin S1 head (a = 275 A) were also recorded. The Bragg spots, only 5 pixels apart, were resolved but were not sufficiently separated to process these data. Changes in the detector design which will improve the DOE and spatial resolution are outlined. The overall performance showed that this type of detector is well suited for x-ray scattering investigations with synchrotron sources.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- 1991
- Bibcode:
- 1991STIN...9120464S
- Keywords:
-
- Apertures;
- Charge Coupled Devices;
- Crystallography;
- Fiber Optics;
- Performance Tests;
- Proteins;
- Radiation Detectors;
- Tapering;
- X Ray Diffraction;
- Bragg Angle;
- Crystals;
- Data Reduction;
- Image Intensifiers;
- Lysozyme;
- Pixels;
- Quantum Efficiency;
- Spatial Resolution;
- X Ray Scattering;
- Instrumentation and Photography