ABSTRACT
This appendix describes the different types of counters that may be used for recording the diffracted intensities in x-ray diffraction experiments-Geiger, scintillation, proportional, and semiconductor counters-as well as the use of pulse height analyzers to improve the peak-to-background ratio. (For a more thorough treatment, see Cullity [1978] and Barrett and Massalski [1980].) All electrical counters suitable for x-ray diffraction experiments depend on the power of the x-rays to ionize atoms, either of a gas (Geiger and proportional counters) or of a solid (scintillation and semiconductor counters). With regard to quantitative texture analysis, mainly three aspects of the different counters are of importance:
An incoming x-ray quantum results in an electrical pulse of the coun-• ter. With increasing number of x-ray quanta, that is, with increasing counting rates, however, the time interval between the pulses decreases and may become so small that successive pulses can no longer be resolved by the counter, which leads to counting losses at high counting rates. The counter • effi ciency describes the fraction of x-ray quanta that is indeed able to initiate an electrical pulse in the counter. Both absorption of x-rays in the counter window and passing of x-rays through the entire counter without being absorbed by the recording medium decrease the ef ciency. In most counters, the output voltage is proportional to the energy of • the x-ray photon (see below), and the energy resolution is a measure for this proportionality between the size of the voltage pulse generated by the counter and the energy of the absorbed x-ray quantum.
