Subject: Faraday cup positions for the standard sample holder have been updated on the system.
From: "James W. Conway" <jwc@snf.stanford.edu>
Date: Fri, 13 Jul 2012 15:35:12 -0700

Greetings:

I noticed that the center position for the Faraday Cup (FC) on holder for the USH had shifted slightly Two weeks ago, so I updated the positions then.  Today I was working on the STD Sample Holder and noticed that it was now off a few tens of microns, possibly due to the change I made last week.  There may also be some wear on the Standard Sample Holders kinetic mounts that is giving us these positional errors which I will look into next week...

While the two holders have the Faraday Cup on holder plates in the same position there is a slight offset in the actual drilled hole locations. 

So this afternoon I updated the positions to the Standard Sample Holder Faraday Cup and checked and made a minute adjustment on the Faraday Cup on stage as well saving both to the database for everyone.

Users working over the weekend and this week are requested to carefully check after your initial beam current measurement if beam spot position is centered in the  FC hole position and report any offsets observed to me.

(There is a position in the pull down menu for the Beam Measurement panel for 'current position' if you find either Faraday cup off center which will allow you to drive manually to the hole and perform the measurement.)

Users whom work on the Universal Sample Holder (USH) should check the position and center into it carefully and then save the position in the Stage control (Position Tab) to your account.

It is critical to accurately position the beam into the FC hole before making a beam current measurement or you will be reading the lower specimen current value rather than the actual Beam Current required for proper dosing of your exposures.

Thank you for your support!

James Conway