A geiger counter concave grating spectrometer for measuring intensities of X-rays of wavelengths between 20 and 400A

• Main Author: Rogers, J. L.
• Language: en
• Published: University of Canterbury. Physics 2013
• Online Access: http://hdl.handle.net/10092/8162

It was decided to attempt the construction of a spectrometer which would make possible the precise measurement of intensities of x-rays in the wavelength range 20-400A. A Geiger counter was chosen as the detector and it was decided to use a concave grating so that a resolving power comparable to that of modern photographic spectrographs could be obtained. The spectrometer was constructed and adjusted and an estimation was made of the effect on the focus of errors in the adjustment. A Geiger counter was constructed and was fitted with a thin celluloid window to permit the entry of the soft X-radiation. When it was found that the plateau position the counter drifted seriously, an electronic method was designed to overcome this drift. Several tests were made on the performance of the spectrometer. After a further adjustment the error in focus was found to be negligible. It was shown that the counting rate, when corrected by a calibration obtained with two radium needles, was accurately proportional to the intensity of X-radiation received. An attempt was made to measure the broadening, by the instrument, of an X-ray line – only partial success was obtained. And finally, the width of the two principle lines of the tungsten emission doublet NIV,V – NVI,VII were measured and a previously unreported component of this spectrum was found. There is some evidence that this line is a satellite of the NIV – NVI transition