The Scintillation Counter
The scintination counter is a relatively new instrument for the detection and measurement of nuclear and atomic radiations. Light produced in a fluorescent material by the incident particle or quantum Is picked up by a photomultiplier tube. The resultant photoelectric emission is amplified in the photomultiplier by a series of secondary-emission stages. This paper is a review of the present state of knowledge regarding the characterstics of the counter and the details of Its operation.
Microsecond Measurement of the Phosphorescence of X‐Ray Fluorescent Screens
Microsecond square‐wave x‐ray pulses, repeated a thousand times a second, were obtained by operating an x‐ray tube directly from a radar pulser. The phosphorescent build‐up and decay of light emitted by fluorescent materials when irradiated by the x‐ray pulses was observed with a multiplier phototube connected to an oscilloscope. Oscillograms of CaWO4 (radiographic intensifying screen) and BaSO4 indicate simple exponential response, with decay to 1/eth intensity in 6 and 0.8 microseconds, respectively. MgWO4 and Patterson B (fluoroscopic) and D (photofluorographic) screens were found to complete their main response to microsecond excitation in 10 to 100 microseconds, but their decay is not exponential.
PHOTOGRAMMETRY AND ITS USES IN HIGHWAY PLANNING AND DESIGN
PHOTOGRAMMETRY MIGHT BE DESCRIBED AS THE PROCESS OF CONVERTING PHOTOGRAPHS INTO CONTOURED TOPOGRAPHIC MAPS. FORMERLY GROUND SURVEY METHODS WERE CONSIDERED THE ONLY RELIABLE MEANS OF OBTAINING ACCURATE TOPOGRAPHIC INFORMATION. IT IS NOW POSSIBLE TO DEVELOP TOPOGRAPHIC MAPS OF SPECIFIED ACCURACY BY MEANS OF AERIAL PHOTOGRAPHS WHICH ARE THEN SUBJECTED TO A SERIES OF PHOTOGRAMMETRIC PROCESSES SO THAT MAPS MAY BE DRAWN AT SCALES USEFUL IN HIGHWAY LOCATION AND DESIGN. /AUTHOR/