In order to prevent this, filters are placed in front of the detector, which allow most of the x-rays to get through, but prevent the protons from getting through to damage the detector. A detector with a filter placed between it and a source of x-rays. Filters are frequently made of mylar film. Figure 2 is a graph of the penetration of protons and helium ions in mylar. For example a 1 Mev proton penetrates about 18 microns, and a 2 Mev proton penetrates about 55 microns.
Filters do affect x-ray detection.
They block the numerous low energy x-rays and reduce the dead time of the detector. Below is a series of spectra taken with various mylar filters in place, and at various energies. 3 High energy PIXE spectrum of a superconductor in vacuum with 200 um mylar filter. 4 High energy PIXE spectrum of a superconductor in vacuum with 300um mylar filter. Notice that while many of the peaks are smaller for the 300 um filter, the calcium peaks are reduced to a greater degree.