Electron diffraction diameter measurement

[hawaiifiver]

Hello

In an electron diffraction experiment usually the diffraction rings are blurred. My question. If measuring the diameter, should I measure to the inside of the ring, the outside, or take a guess where the middle of the ring is and measure to there? Thanks

 

[Jacques_L]

In an electron diffraction experiment usually the diffraction rings are blurred. My question. If measuring the diameter, should I measure to the inside of the ring, the outside, or take a guess where the middle of the ring is and measure to there?

Yes, the monochromatic character of a cathodic ray is never as good as for the $K\alpha$ of cobalt, copper or molybdenum we use in radiocrystallography.
We always take the middle of the ring on Debye-Scherrer films, of the spots on Laue diffractograms, the summit of the peaks on paper diffractograms.

So guess the middle of your rings. No better way.