Problem raith SNF 2010-10-14 16:27:01: faraday cup on USH does not measure consistently -spurious

[jwc at snf.stanford.edu]

Today load of Universal Sample holder for exposure failed the test of the faraday cup on holder.  This seems to be a spurious problem and may be related to a change in the position of the contact slider below the sample holder on the stage.  The readings while often correct exhiobit a large unacceptable sigma in the measurements (N = 10 for each FC position) while FARADAY CUP on stage reads consistently within range of 0.00005 nA.
Raith has been contacted and I upgrade a service request today.
Users of the STD. Sample holder are requested to check and coompare Beam I reading from each FC tyo assist me.
James