Bremsstrahlung Emission Measurement from Thick Tungsten Targets in the Energy Range 12 to 300 kV

摘要

X-ray spectral measurements were made using four commercial, tungsten-target, x-ray units operating between 12 and 300 kV. The absolute intensity as well as the spectral distribution was measured. The effect of varying the tube current, target aperture, and detector aperture was investigated. The intensity from two constant-potential units was proportional to the tube current, but two self-rectified units displayed a departure from linearity as the tube current increased. As the target aperture area was increased, the photon intensity increased rapidly at first, but then leveled off to a constant value. The intensity was found to vary directly with the area of the detector aperture, but the spectra became distorted when the aperture was increased to where the counting rate exceeded 1.2 x 104 counts/sec. Sodium iodide scintillators, germanium, and silicon semiconductors, and a xenon proportional counter were used to measure the spectra. The measurements were corrected for Gaussian broadening, efficiency, escape peak losses, Compton scattering, and energy linearity to obtain an estimate of the undistorted spectra incident on the detectors.