Preliminary HMS
Q1 and Q2 settings (Tanja Horn)
The Q/D ratios should be constant if the Quad and Dipole effective lengths are constant (and the Hall probe is any damn good). Some of the random variation seen may be due to the cycling procedure (or lack thereof).
The Q1 setting appears flawless over a large dynamic range. (We're assuming the effective length is constant, so a measurement of the field alone is sufficient.)
The Q2 setting is good, although it does appear to vary systematically at the 0.1% level. We can expect a slight vertical motion of the waist in hsxfp vs hsyfp, and perhaps a slight momentum dependence in the reconstruction.
Q3 setting (Tanja Horn)
The Q3 setting has problems. This is why users shouldn't drink and edit the HMS field setting program. Actually, users who don't drink shouldn't edit the HMS field setting program. Jochen and I properly took into account the residual field of the iron before FpiI (at least down to 1 GeV/c). We would never have run FpiI like this, but obviously we ran FpiII like this. Screwing up the Q3 setting then leads to significant rotation of the delta focal plane, or a dependence of delta on hsxpfp. (See below.) With Hall C resolutions, a 0.25% mis-setting is noticeable in the reconstruction. The mis-tuning here is several times larger than my threshold and momentum dependent.

HMS focal plane rotation (Tanja Horn)
If this mis-setting were due to an offset problem, we would tend to blame it on Q3 because it has the lowest fields. However, this figure from Tanja makes it look like at least one of the quad calibration constants is just plain wrong.

Sept 8, 2003, by Dave Mack