The Cadmium Sulfide X-Ray Detector

The CdS x-ray detector is compared with the photo-multiplier x-ray detector. Reduced to the same solid angle the sensitivity of the CdS x-ray detector is of the same order of magnitude as the sensitivity of the photo-multiplier x-ray detector. As the internal amplification of the primarily released electron currents in CdS is of the order 103 to 104 compared with the amplification in the multiplier tube of ½×106 the conversion process of x-ray quanta in slow electrons in CdS must be more efficient than the corresponding processes in the combination crystal phosphor screen photo-multiplier. Calibration curves show a linear relation between photo-current and intensity of x-rays at low irradiation levels. At high irradiation saturation effects occur. Oscilloscope curves of the response at 60 x-ray pulses per second are given. At strong irradiation the photo-current over a long time increases in a completely reversible way. X-ray intensities as low as 150 quanta CuKα per second are registered with a circuit employing a WL 759 trigger tube.