Determination of x-ray spectral distribution from transmission measurements using K-edge filters

Accurate high-resolution x-ray spectral distributions can be obtained with an intrinsic germanium crystal. This technique is difficult to implement since it requires expensive, complicated, and bulky equipment. If energy resolution requirements are relaxed, then the above drawbacks can be overcome and an x-ray spectrometer that is small, inexpensive could be built. A technique that meets these requirements is described here. X-ray spectra with about 7-keV resolution can be achieved by obtaining transmission measurements through a number of different K-edge filters. Using these measurements, a system of equations is set up and solved giving the required spectral distribution. The technique has been tested using 80, 100, and 120-kVcp x-ray beams with total filtrations of 3.78, 5.78, 9.06 mm A1, and 3.78 mm A1 + 0.137 mm Ho. The results show that the calculated spectra closely resemble tabulated spectra. The errors ranged from 3% to 13%. The half-value layers (HVL) were also calculated and compared to the HVL obtained from tabulated spectra and were found to differ by about 7%.