Post by RichD Post by Martin Brown Post by firstname.lastname@example.org
Ever so slightly different values are quoted in various references.
The value I use is one seen frequently, 6.02214076 E23 . Other
Unless you are doing something very unusual it makes little difference
beyond 4 sig fig.
Physicists care about it when ... ion counting in mass spectrometry
What exactly is ion counting, and how?
Imagine a photomultiplier tube but without the glass envelope and
already in a vacuum chamber. Hit it with an ion at 8kV acceleration and
it spalls a cascade of electrons. You don't need so many gain stages.
There is a limit to how quickly it can recover (dead time) - ours used
to max out at about 10MHz. They can also be run at a much lower gain in
a pseudo analogue sort of way as a current detector.
This lot claim to be up to 1GHz ion count rates now. No idea if it is
genuine and works as advertised. I don't work on that stuff any more.