Angular dependence of the detection limit of pixe

A Mylar foil of 10-μm thickness was bombarded with 6-MeV proton beams. Continuum X-rays produced have been measured with a Si(Li) detector over an angular range thetasub(L) = 43.50-148.50 with respect to the proton beam. On the basis of these continuum X-rays measured, the detection limit of PIXE has been estimated as a function of the detection angle and atomic number of the element to be detected; the measurement at an angle of thetasub(L) >= 1350 is found to be favorable to obtain high sensitivity. Continuum X-rays from Mylar foils of 4-, 10-, and 40-μm thickness bombarded with 6- and 20-MeV protons were also measured and the effect of escape of secondary electrons from the target on the continuum X-ray intensity is discussed. (orig.)