Many moons ago we published a paper (Donovan, Pingitore and Westphal, 2003) on electron backscattering and the effects on that by atomic mass vs. atomic number.

The bottom line is that mass has essentially zero effect on backscatter loss, while the BSE effect is essentially solely related to the effective nuclear charge of the nucleus, therefore the effect is almost entirely due to electrostatics. This claim is something that physical scientists generally accept after a few minutes of thought, but some, at least at the time, seemed surprised by our results.

After the paper was published, we had a response from Stephen Reed who suggested our "proposal should be treated with caution, pending more rigorous testing". Of course we are all for caution and more rigorous testing, but we still stand by the claim today, and more recently we have repeated these measurements and calculations, and found them to be reproducible both empirically, and theoretically, based new measurements and on the latest Monte Carlo models, as seen above in this topic.

For those interested in the gory details, the full paper and the response by Reed and our response to Reed's response are attached to this post:

https://probesoftware.com/smf/index.php?topic=1111.msg7448#msg7448However I had noticed soon after we had published our response to Reed back in 2003, that there is a small typo in our response that we should have caught at the time. The error is highlighted in yellow:

Can you see the math error?

Well, since the largest mass effect of an electron interacting with a hydrogen nucleus, in the case of a perfectly elastic collision (180 degrees backscatter) with a single proton, the energy loss is roughly 1/2000. And for higher mass atoms, the effect is much smaller! OK, so you spotted the math error? Yes, 1/2000 is not 0.2% as stated in our response, it is only 0.05%. Doh!

So, yes, the mass effect on electron backcattering is even smaller that we claimed!

There will be more to say on this subject, but please feel free to make your own measurements and calculations and share them with us.