Detection of Carbon with X-Ray Scanning Microanalyzer

Abstract

A new type gas flow proportional counter for detecting ultra-soft X-rays from low elements has been devised. Construction and performance of this counter are given in detail. Pulse height distribution curves of output by carbon, aluminium and magnesium K X-ray emissions show that the resolution of the counter for X-ray energy is almost of its theoretical value and that the pulse height voltage is proportional to the energy of X-ray radiation.
For detection of X-rays of the wavelengths longer than 20Å with a proportional counter, absorption of window material is a matter of serious concern. Polycarbonate is used; it is easily made into thin films: thickness of a few thousand Å gives the film enough tensile strength to withstand pressure difference between inside and outside of the counter and is sufficiently non-permeable to gas. At 5000 Å of thickness, the film absorbes 50% of 44 Å carbon K X-ray emission by cal-culation.
Analytical results are given on carbon on the surface of iron during casting observed with an X-ray scanning microanalyzer provided with the counter described above.