The development and application of the phosphor-photomultiplier combination to the detection and spectrometry of low energy quanta

摘要

Although the phosphor-photomultiplier combinationprovides an instrument of great versatility, up to quiterecent times it has been employed almost solely in thenuclear physics field. This thesis describes someexperiments designed to determine the effectiveness ofthe device for the detection and spectrometery of lowenergy X-ray quanta such as are employed in X-raydiffraction work. The present experiments were allcarried out using Copper K radiation (8keV).A coincidence pair was the principal experimentalarrangement investigated, as this provided a means ofgreatly reducing the number of dark noise pulses. A twochannel pulse height analyser was devised to enable thedistribution of the total number of photoelectrons releasedin each scintillation to be determined. The single phototubecounter was also investigated and the results obtainedconfirm its practibility for X-ray diffraction workprovided photocathodes of high quantum efficiency (15% atleast) are employed. Diffractometer records are includedwhich illustrate the practical performance of both the singleand coincidence counters.The absolute accuracies of the measurements madethroughout these experiments are relatively poor sincepractically no calibrated test instruments were availableat any stage of the project. However, the satisfactoryoverall performance of the equipment is evidenced by thediffractometer records which generally are aS good, if notbetter, than those obtainable on commercial instrumentsemploying conventional detectors.