Hard x-ray spectrometer calibrations using a portable 120 kV x-ray source.

A Cauchois transmission-crystal hard x-ray spectrometer was calibrated by using a portable, compact, battery-powered tungsten x-ray source having 120 peak kilovoltage. The source emission region was characterized by recording high-resolution 2D x-ray images and was found to be composed of three emission regions having a 400 µm overall extent. The absolutely calibrated source fluence was measured by using a calibrated silicon drift detector and was in good agreement with the spectrum calculated by the SpekPy code. High-resolution spectra of the W Kα and Kβ lines in the 57-70 keV energy range were recorded on image plate detectors by the Cauchois spectrometer and provided excellent calibrations of the spectrometer's dispersion and spectral resolution. The minimal effect of the source size in the spectral lines recorded on the spectrometer's Rowland circle and the source-size broadening of the spatial lines recorded well beyond the Rowland circle were analyzed. The integrated reflectivity of the spectrometer's quartz (101) crystal was measured by using the absolutely calibrated 59.318 keV W Kα spectral line emission and was in agreement with previous integrated reflectivity measurements performed at the National Institute of Standards and Technology. The well-characterized portable 120 kV x-ray source provides a convenient and cost-effective way to accurately calibrate the sensitivity, dispersion, spectral resolution, and source-size broadening in the spectra recorded by high-resolution x-ray spectrometers operating in the hard x-ray range. The absolutely calibrated source fluence can also be used to calibrate x-ray detectors at energies in the 40-100 keV energy range.