From emma@slac.stanford.edu Wed Jan  4 12:27:39 2006
Date: Wed, 4 Jan 2006 10:30:15 -0800
From: "Emma, Paul J." 
To: "Weidemann, Achim W.", 
     "Anderson, Scott D." 
Cc: "Carr, Roger",
     "Rago, Carl E.",
     "Wolf, Zachary R."
Subject: Re-measure QE-072?

Achim and Scott,

I have analyzed the three sets of QE data and conclude that the variation in polynomials is large enough to warrant significant magnet controls software modifications for the LCLS.  I won't elaborate on this yet, but I simply comment that my conclusions are completely based on one of the three quads having significantly different polynomial than the other two.

The "outlier" quad is QE-072 and I would like to ask if you can simply re-measure this one to confirm my conclusions.

Your original data for this quad is at: 

http://www-group.slac.stanford.edu/met/MagMeas/MAGDATA/LCLS/quad/QE-072/strdat.ru3

The other two are at:

http://www-group.slac.stanford.edu/met/MagMeas/MaGData/LCLS/quad/QE-002/strdat.ru1
http://www-group.slac.stanford.edu/met/MagMeas/MAGDATA/LCLS/quad/QE-072new/strdat.ru7

This QE-072 quad has 3% lower linear slope than the mean of the other two (from I = 0 to 20 A), and twice the remnant field.

I would like to confirm this by repeating the magnetic measurements for this one quad (QE-072) as consistently as possible with respect to the original measurements (same probe and power supply if possible).

I hope you have time to do this test.  Even a simplified version would be helpful.

The procedure I originally prescribed is attached here again.

Please also note that the 3rd QE magnet, previously referred to as "QE-072new", should be called "QE-004".  Achim and I found a weak stamp on the laminations today with this number (also in black marker).  It would help if you could add clear and permanent labels on the top of the magnets so there is no confusion in the future.  I am expecting to use these magnets again in the LCLS if the QE-072 measurements repeat well.

	Thanks,
	-PE

    [ Part 2, "QE_meas.doc"  Application/MSWORD  36KB. ]
    [ Saved as QE_Meas.doc in this directory ]