General
Effect of Vertical Offsets (by Henk Blok)
Preliminary SOS
P = 0.9 (by Chuncheng Xu)
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.
Sept 8, 2003, by Dave Mack