Muon Offline Meeting
			====================
			Wednesday, 6-March-2002


		             Minutes

----------------------------------------------------------------------
All - Definition of the W/Z Data Set
      ==============================

Michael Schmitt gave a summary of recent discussions of the details
and particulars of the W/Z Data Set.  Many of the differences of
opinion had been worked out in advance.  The details can be seen
from the transparencies.  Additional points:
  1- apply loose cuts now, tighten later
  2- do not cut on isolation
  3- apply the loose, sliding cut on Ehad currently used
     in the definition of the high-pT muon sample.
  4- Ken is encouraged to design a summary object for the L3
     decision (since the L3 quantities will not be saved).
     This would retain a copy of all cut quantities as well
     as some more detailed information about the muon track.
     He will discuss this with the offline experts.
  5- Henry has discussed the possibilities for obtaining
     muon volunteers with Jonathan Lewis, who has some very
     concrete and useful ideas on how to do this.  We will
     invite Jonathan to the next meeting to make a short
     presentation.
  6- There will be no attempt to make electron and muon data
     sets orthogonal at this time, because it renders the
     muon data set dependent on the electron data set, and
     vice-versa.

----------------------------------------------------------------------
Victoria Martin -- CMP Alignment
                   =============

Victoria has done a lot more work on the problem of the CMP Alignment.
She identified five periods of CMP Wall positions.  The nominal
positions are supplied by Kevin Lannon on the basis of the hardware
position readout device.  They have been entered into the data base.

Victoria reviewed her strategy for deducing vertical and horizontal
offsets from fitting mean dX vs phi. For the most part, the mis-
alignments are horizontal, and they are different for the three
(out of five) periods with good muons.  Making corrections for these
misalignments helps the dX vs phi curve, but there are not enough
muons to do stack-by-stack alignments, yet.  There is some puzzling 
structure for the bottom region.

Victoria has performed checks of her results: 1) she validated the
whole procedure using MC with purposeful offsets.  2) she applied
her corrections to real data and sees that the offsets are almost
entirely removed as a function of phi.  

Unfortunately, when she looks at the delta-X distribution, she finds
that the overall width is hardly reduced.  The strange shapes that
were observed earlier are now replaced by an even, bell-shaped curve,
but apparently there still is an additional source of smearing
beyond multiple scattering and measurement errors.  The width of
the distribution is about 2.5cm.  We suspect that stack-by-stack 
corrections are still needed.

----------------------------------------------------------------------
Jim Bellinger -- BMU Progress Report
                 ===================

The IMU now uses the new muon geometry objects, including hits and
stubs.  Some internal structures have been retained, but these do
no harm.  The stub finder has been revised slightly, and time offsets
have been incorporated.  They are important for successful reconstruction.

According to studies with simulated events, the reconstruction efficiency
is reasonably high.  From the data we learn that the Z-position between
the inner and outer layers agree to about 10cm, which is good.

It was agreed in the meeting to make this new code the default for
muon reconstruction in production, and to gradually remove the old
code from the repository.   

This represents a very important milestone in muon reconstruction.

----------------------------------------------------------------------
Alexei Varganov -- An updated W-peak PR Plot
                   =========================

Alexei presented a new version of the W PR plot.  He used Eric's list
of good stores, which begins with the February data.  Alexei noted
some discrepancies between streams A and B, which appear to come from
subtle differences in the reconstruction code and calibrations.

Alexei used about 2.5 pb-1 from stream A.  He found 349 events in the
data, and presented a series of `N-1 plots.'  The new plot was 
approved.

----------------------------------------------------------------------
Slava Krutelyov -- A first look at the G3X Problem
                   ===============================

Slava shows that the rms and offset are wrong when using the G3X
(Geant-based extrapolator).  The offset goes away when he forces
Geant to use a smaller step size.  The rms, however, is large, about
a factor of root(2) larger than obtained from MExtrapolator.  He ran
the simulation without multiple scattering, which surprisingly had
no impact.  This means there is a bug somewhere, and he is fairly
certain that geant somewhere is turning multiple scattering back on.
This appears to happen between the COT and the TOF. 

Slava pointed out that we will need to think about the CPU cost
of a much smaller step size.

----------------------------------------------------------------------
M.Schmitt