[Halld-tagger] Excitation dependence compared with Tosca

[Daniel Sober]

The attached table and figure (and the Excel spreadsheet it comes from) 
shows a comparison between the field/current ratio (at pole center) from 
the data and from Tosca.  Since your spreadsheet gives the current only 
in "PPM", I have adjusted the ratios to make them agree at 1.5 T.  The 
consistency at 0.75 T, 1.5 T and 1.7 T looks quite good.  (I have 
connected the measured points by straight line segments to make it 
easier to see where they are.)
                     Measured ratio (P1)        Tosca ratio
     0.75 T    2.0867                                 2.085 (average of 
0.6 and 0.9 T)
     1.50 T     2.0307                                2.0311
     1.70 T    1.8461                                 1.8582
This is important in case we have to interpolate between the maps to run 
at an excitation other than 1.5 T.

The measurements at 0.1 T and 0.0536 T are way off the curve.  Since the 
Hall probes and the NMR agree, the only sensible explanation is an 
offset in the power supply reading.  Does anyone have a calibration of 
the current reading?  As long as we have the NMR probe, I guess the 
current is not important.

Dan
> -- 
> /Daniel Sober
> Professor
> Physics Department
> The Catholic University of America
> Washington, DC 20064
> Phone: (202) 319-5856, -5315
> E-mail: sober at cua.edu <mailto:sober at cua.edu>/
>

-- 
/Daniel Sober
Professor
Physics Department
The Catholic University of America
Washington, DC 20064
Phone: (202) 319-5856, -5315
E-mail: sober at cua.edu/
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