Detection of X-ray fluorescence of light elements by electron counting in a low-pressure gaseous electron multiplier

Ionization electrons deposited by soft X-rays in a low pressure (10 Torr) gas medium are efficiently counted by a multistage electron multiplier, providing an accurate measurement of the X-ray photon energy. Energy resolutions of 56-28% FWHM were measured for X-rays of 110-676 eV, recording electrical induced charges or visible photons emitted during the avalanche process. It is demonstrated that a combined analysis of the number of electrons and the electron trail length of an event, provides a powerful and competitive way of resolving ultra-soft X-rays. We present the experimental technique, discuss the advantages and limitations of the Primary Electron Counter, and suggest ways to improve its performances. (orig.)