Alignment Study Group minutes ? 28 June 2000

Specific Goals for the November Run
-------------------------------------

This list was posted on 30 May 2000.  It should be regarded as a dynamic
list to evolve as we continue our discussions.  Additions and comments
are interspersed as appropriate.

   a. Study chamber inter-alignment, i.e., wire spacing/positions.
   b. Study intra-chamber alignment, i.e., between planes.

Maher’s posting of 1 June 2000 indicates that he has code which was
written and used for alignment studies on data taken in August 1997.
This code needs to be modified from F77 to F90 and Valpo (Paul Nord) has
agreed to do this.  Maher will need to make some structural changes for
this code to take advantage of the Kahlman filtering algorithm.  The
code will then be tested at Valpo with Monte Carlo events.

The following are notes from a discussion about alignment techniques for
the wire and plane positions which emphasized those techniques for
determining the z-position of the detector planes.

We should expect to know the position of the chambers in x,y to ~150
microns from the construction process.  A visual survey should be able
to determine the x,y position to ~25 microns.

It was suggested that the z-location of the chambers could be determined
with the detector assembly mounted in the cradle and positioned in a
high energy pion beam in M11.  If the incident particles were to make a
relatively large angle with respect to the normal to the chamber planes,
the straight line trajectories (no magnetic field) could be used to
determine the relative z-location of the planes.  The precision of these
z-measurements will need to be tested with Monte Carlo generated
events.  (The MC will run straight tracks with B=0.0, as well as helical
tracks, with B > 0.0.)  The technical questions of how one could/would
be able to move the detector between the M11 and M13 lines and assure
that the changes in the chamber locations would be minimal were not
addressed.  [c.f. Vladimir’s notes: TN-39 "Alignment of "muon beam -
magnetic field" and "muon spin ? magnetic field" systems", Chamber Note
"The E614 Detector Alignment", 18 Feb.2000.]

   c. Study detector alignment w.r.t. the magnetic field

Bob Tribble has posted a proposed method of testing the alignment of the
detector w.r.t. the magnetic field on 3 July 2000.  We will have a look
at this in the next alignment meeting.

   d. Study detector alignment w.r.t. the beam.
   e. Study detector alignment properties with cosmic rays.

The Valpo group (Don) has agreed to look after the use of cosmic rays
for alignment studies.  (See comments below.)

   f. Study the stability of the cradle using camera monitoring.

Robert pointed out that we should have independent data (apart from
tracking) to determine whether the cradle is moving.  The camera
arrangement which is being developed by Jerry at Regina seemed
appropriate and he should be contacted to plug into this conversation.
Maher will contact him.

Support needed to achieve these goals.
---------------------------------------

   a. Access to specific data.
   b. Software to read/process data needed.
      - Presumably this is all in place in MOFIA.  (Is this correct?)
   c. Hardware required to take measurements.
   d. Beams needed for alignment studies -
      - Muons/positrons with magnetic field on
      - Muons/positrons with magnetic field off
   e. Monte Carlo codes for detector in November.
      - Presumably all these MC codes exist.
   f. Monte Carlo codes for magnetic field on/off with beam.
      - These exist (see above).
   g. Monte Carlo codes for cosmic rays; field on/off.
      - These codes likely exist as done by summer student, Martin
Shotter.  The Valpo group has agreed to be responsible for alignment
studies with cosmic rays and will attempt to locate and test the codes
which Shotter has developed and on which he has reported.  [Don has
located the codes on alph04 and will download them to Valpo for testing
and development.]


Don

-------------------------------------
donald.koetke@valpo.edu
www.physics.valpo.edu/faculty/dkoetke/

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