Multiwire proportional counters for use in area X-ray diffractometers
The multiwire proportional counter is at the time of this writing the only type of two dimensional position sensitive X-ray detector capable of collecting diffraction data accurate enough for solution of new protein structures. The first diffractometer system to use this type of detector (the Mark I diffractometer system) was assembled at the University of California, San Diego and has collected the data used to solve four new protein structures. Similar diffractometer systems using a single thin, flat multiwire counter are now being constructed in many other laboratories around the world, and several of these will routinely be collecting good diffraction data from protein and perhaps even virus crystals within two years. A table describing these other systems is included here. The next step in the evolution of area diffractometer systems based on the multiwire proportional counter is more complete coverage of the solid angle of the diffraction pattern: more complete than the 10% to 40% coverage possible with one flat multiwire counter. The phenomenon called ''parallax'' makes it impractical to intercept the whole diffraction pattern with one flat xenon-filled multiwire counter. Two strategies for dealing with parallax are now being pursued. One strategy involves adding a spherical drift region to the front of a flat multiwire counter and adetector using this idea will be described. The other strategy, the one being pursued by the author, involves building an array of flat detectors arranged to approximate a section of the surface of a sphere. The array of flat detectors gives more flexibility in crystal-to-detector distance and distributes the dead time over many detectors, allowing the full array to have a high counting rate capacity even using only medium speed (2 microsecond) position readout circuits for each individual detector.
- Research Organization:
- Department of Physics, University of California, San Diego, La Jolla, California 92093
- OSTI ID:
- 6052587
- Journal Information:
- Trans. Am. Crystallogr. Assoc.; (United States), Vol. 18:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MULTIWIRE PROPORTIONAL CHAMBERS
DATA ACQUISITION
SPATIAL RESOLUTION
X-RAY DETECTION
X-RAY DIFFRACTOMETERS
ELECTRODES
POSITION SENSITIVE DETECTORS
PROTEINS
PULSE TECHNIQUES
DETECTION
DIFFRACTOMETERS
MEASURING INSTRUMENTS
ORGANIC COMPOUNDS
PROPORTIONAL COUNTERS
RADIATION DETECTION
RADIATION DETECTORS
RESOLUTION
440101* - Radiation Instrumentation- General Detectors or Monitors & Radiometric Instruments