Spectral distributions of X-rays produced by a General Electric EA 75 Cr/W tube at various applied constant voltages

Spectral distributions of x-rays generated by a General Electric EA 75 Cr/W dual target x-ray tube have been measured using exciting voltages of 20, 30, 40, 45 and 50 kV c.p. A carefully characterized and previously described lithium-drifted silicon detector was used and corrections were applied for second order effects in the detection system and for detector efficiency. Relative errors are believed to be of the order of 1% over most of the range covered (4 to 50 keV), increasing to about 10% over the lower range of photon energies (2.5 to 4 keV). Although the resolution of the detector is limited, it was nevertheless possible by computation to separate groups of characteristic spectral lines from continua and to determine self-absorption jump ratios in these continua. Spectral distributions obtained using chromium and tungsten targets are compared with earlier data of Birks and his collaborators (X-Ray Spectrochemical Analysis. Wiley-Interscience (1969)) and with the forms of continua predicted by Kulenkampff's equation (Ann. Phys. K.; 69:548 (1922)). Agreement is only fair. The experimental method employed for studying spectral distributions is believed to be the most accurate and reliable now available and is particularly convenient in terms of the rapidity with which distributions can be measured. Further work is required to remove remaining uncertainties concerning the generation of x-rays at thick targets. (author)