Charge integration in external PIXE–PIGE for the analysis of aerosol samples

The beam current in an external-beam PIXE–PIGE is difficult to accurately measure due to ionization along the beam path in the atmosphere. Charge integration was measured using a homemade Faraday cup, and assessed by the peak area of Ar Kα X-rays, which were induced by protons near the sample. The X-ray peak integral from a thin Fe reference sample, which was positioned between the exit window and the Faraday cup, was determined to evaluate the performance of the homemade Faraday cup. Moreover, the effects of different membrane filters and samples with different elements on the beam current measurement of the aforementioned methods were studied by placing different blank films or reference standards behind a reference Mn target. The results indicated that the charge measurement of the homemade Faraday cup was reliable for external PIXE–PIGE analysis of aerosol samples.