In designing the Xray machine, we always want a monochromatic Kalpha radiation of X-ray source. For this purpose we generally put a filter to reduce the k beta radiation but still we get some k beta intensity.
My question is If we design a filter material whose K absorption edge lie exactly at K beta radiation peak of targeted source then maximum possible absorption take place. So is there any problem to design this material or it will affect the X-ray performance.
There are several issues to consider:
1. Absorption is a probabilistic event - most, but by no means all, of the Kbeta radiation will be absorbed. Some of the Kalpha radiation will be absorbed as well. It is not possible to design a step filter for x-rays. All filter materials will absorb x-rays at all energies. It is just a matter of atomic number, density and thickness.
2. The filter will reduce the overall output of the tube. This may or may not affect the performance of the tube or system, depending on the system requirements.
3. One way to produce monochromatic x-rays is to use refraction off a crystal. See https://xpssimplified.com/xray_generation.php.
Dear Yusuf Khan ,
Thomas L Morgan is right.
If you could find such a filter, the K-alphas would always also be attenuated a bit too.
But you cannot design such a filter (K-edge just at K-beta position) due to the fact hat you are not able to shift a) neither the K-edge energy nor b) the K-beta energy. They are fixed due to the properties of the energy levels of the atomic shells.
For edge and fluorescence line energies please have a look for example at:
https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwj0t9apuvPlAhXG_qQKHVmIBHsQFjAAegQIAhAC&url=https%3A%2F%2Fedisciplinas.usp.br%2Fmod%2Fresource%2Fview.php%3Fid%3D1107326&usg=AOvVaw1fW_O5AbiUgaxmheoJ-ShW
The best way to get rid of all photons other than the K-alphas is to use some kind of monochromator, as Thomas already stated above.
The purpose of Kbeta filters is not just to eliminate Kbeta intensity but to also minimize the continous spectrum (bremsstrahlung) of x-rays. Few things to keep in mind,
1. Increasing the thickness of filter to reduce the Kbeta further will also decrease the Kalpha intensity.
2. Shifting the K absorption edge toward Kbeta (by changing filter material) will reduce Kalpha intensity and increase background noise.
3. Significant presence of Kbeta can also be due to Spectral contamination, this generally happens with the old tubes. If possible you can compare the measurements of old vs. new tube. If you try this, then pls. also share your findings.
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