Beam model should state probe type about dxtbx HOT 3 OPEN

For completenss, suggest we select the names from above as

neutron
x-ray
muon
electron
ultraviolet
visible light
positron
proton

I find it unlikely that we support positrons or muons in DIALS, but ...

from dxtbx.

https://manual.nexusformat.org/classes/base_classes/NXsource.html

The choice of the name probe is perhaps questionable for those of us of a certain age with a fondness for anarchic cartoons, but it is the de facto standard.

from dxtbx.

Actually the QE correction does not take in the Beam model. It should be possible to correct behaviour by setting an appropriate µ factor in the format class. So that's an orthogonal issue - it may still be useful to record the probe in Beam anyway.

from dxtbx.