Application of the electron-counting method to low-Z elemental analysis

We applied the electron counting method, in low-density gas, for ultra-soft X-ray spectroscopy. The method is based on the spatial expansion of photon-induced ionization electron clusters, and the recording of pulse trails formed by individual electron avalanches in a fast multiplication element. A detector, operating at room temperature with low gas pressure, was characterized with Particle-induced X-ray Emission (PIXE) and with electron-induced X-ray emission in a Scanning Electron Microscope (SEM). High detection efficiency for soft X-rays is obtained due to the very thin polymer window between the detector and the radiation source. The low-density detector is blind to Bremsstrahlung and charged-particle background. We present the results of the spectral analysis of characteristic X-rays emitted from low-Z elements, in the energy range 100-1500 eV. The recorded X-ray spectra, using both the information of the number of counted electrons and the length of the electron pulse trail, are unfolded with the help of a computer simulation of the detector response to X-ray photons. This detailed simulation of the electron detection and counting process provides an efficient means for a quantitative spectral analysis and permits the precise reconstruction of complex energy spectra.