[Mott] Mott beam studies update

[Joseph Grames]

Folks,

Recently we tested the Mott dump (empty target) successfully to 35uA, resulting in only modest temperature or vacuum (new!) increase.  Early this morning we had another opportunity and tested up to 75uA to the dump (empty target), more importantly 40uA to a 0.5um Au target with stable and similarly reasonable vacuum condition, also providing an excellent OTR signal from >few uA particularly useful for online compensation of bunch length correlated energy spread.  The last foil tested 0.05um Au is too thin to be free-standing and is backed by formvar.  I reached 40uA but then, quite dramatically, tore the foil at the foil/formvar intersection, presumably a thermal break or beam reaching the formvar - not sure yet.

For those with a JLAB username and password you can look at results yourself:
https://logbooks.jlab.org/entry/3280208

Best,
Joe