ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
Electronic devices intended to visualize x-ray images are intensively evolved on the basis of linear video signal shapers (LVSS): x-ray vidicons, image vidicons with x radiation-to-light conversion using luminophors and scintillators, charge-coupled devices, photodiode arrays and matrices, as well as on the basis of various electro-optical converters: electrostatically or magnetically focused and microchannel image intensifers. Their broad application to x-ray diffraction topography, structue analysis, diffractometry, tomography, and radiography has necessitated (already from 1982) the introduction of a common criterion for calibration of their sensitivity—the flux density of monoenergetic photons. In particular, when calibrating the LVSS it is necessary to find a direct, unambiguous correspondence between this criterion and the amplitude of a video signal. For this purpose, a device has been designed which is used both for absolute calibration of LVSSs and, of course, for a trivial standardization of x-ray counters with respect to their efficiency. This device is based on two commercial gas proportional counters whose position in space is aligned for a successive, one after another, "threading'' of them to the x-ray beam monochromatized by means of the crystal-diffraction scheme (Lukirsky's method). Both counters are identical to each other. Of course, each counter has input and output windows. The beam is shaped by diaphragms and by two slits, horizontal and vertical, with cylinders as "knives.'' One of the slits is scanned in the diffraction plane by a stepper motor. The counters are tested for identity by selecting them depending on their counting properties and energy resolution, with the escape peaks taken into account. All these operations and the rest of the measurements are performed by electronic units in the CAMAC standard, controlled by a microcomputer. On the test monochromatized x-ray beam, the device is interchangeable with a LVSS or a counting detector being standardized. The test beam is monitored. The width of the slit being scanned is shaped up to 10 μm, thereby allowing the LVSS to be standardized for geometrical resolution.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1140761
