Calibration of a PIXE system at Peking University

A method combining particle-induced X-ray emission spectrometry (PIXE) and elastic backscattering spectrometry (EBS) was used to calibrate the PIXE system at Peking University. The selected thin standard samples were typically 50 μg/cm² and the thicknesses of two thick standard samples are 3 mm. The calibration of PIXE system was divided into the calibration curve measurement of thin standard samples and the external standard method of thick standard samples. Both thin and thick samples cover the commonly used PIXE X-ray energy range 1.4–18.0 keV. GUPIXWIN introduces an Instrument factor H to describe the calibration process. It is found that the measured H(Z) curve can be approximated as a Z-independent line with an average value of $3.30\times {10}^{-4}$. The deviation of multiple measurements of a single element is between 0.42% and 4.75%. For thick samples, the incident particles are protons and ³He⁺, a H value of $\left(4.97\pm 0.01\right)\times {10}^{-4}$ was obtained.