Cocoa ME 1

1
Cocoa ME1
James N. Bellinger University of
Wisconsin-Madison 18-Feb-2009
2
How close are we?

• Coded targets tell where chamber surface is
• Hand calculation minus coded target
• Poor agreement

3
ME1/2 Outer layout
Target3mm
SensorBox 63mm
dowel
Sensor mount plate 10mm
Shim 12.1mm outer, (4.6mm inner)
Mount plate 6.35mm
DCOPS
Spacer 35mm
Chamber frame plate 6mm
Chamber Surface
For upper Target topreference Frame ref-
135.45 Sensor center ref-26 (233) DCOPS
center ref- 135.726 Surface DCOPS
center0.276 DCOPS dowel ref-94.45
41.276mm dowel to center
4
ME1/3 layout
DCOPS
DCOPS center to dowel 41.276mm
Mount plate 6.35mm
Spacer 25mm
Chamber frame plate 6mm
Chamber Surface
5
Is something missing?

• Original Cocoa number for 1/3 DCOPS to chamber
  surface seems to be wrong
• The descriptions of the material involved in the
  DCOPS and ASPD mounting for the HSLM are laid out
  in in tree form in
• http//www.hep.wisc.edu/jnb/cms/docs/psl/MEp1.htm
  l
• The chamber frame information is from Wenman and
  I dont have the construction drawings defining
  it.

6
Doing my own optimization

• Use Link info to get ASPD top for ME1/2 outer
  and the distancemeter position for the Transfer
  Plate
• Use offsets from CAD drawings to reach DCOPS
  center positions
• Include profile positions (not at center) and
  calculate a line joining the two points
• Predict profile position at ME1/3 DCOPS
• Use profile positions and CAD information to
  predict chamber surface positions

7
Optimizing

• Use the average of these two surface positions as
  an estimate of the surface at 0T
• Subtract the coded target position (on surface),
  square and form a chi-squared
• Sum for HSLM1-5 only HSLM6 known bad
• Variables
• Xadditional distance between ASPD and DCOPS at
  ME1/2
• Yadditional distance between DCOPS and surface
  at ME1/3

8
X variable definition
Target3mm
SensorBox 63mm
dowel
Sensor mount plate 10mm
Shim 12.1mm outer, (4.6mm inner)
Mount plate 6.35mm
X
Spacer 35mm
DCOPS
Frame plate 6mm
Chamber Surface
For upper Target topreference Frame ref-
135.45 Sensor center ref-26 (233) DCOPS
center ref- 135.726 Surface DCOPS
center0.276 DCOPS dowel ref-94.45
41.276mm dowel to center
9
Y variable definiton
DCOPS
DCOPS center to dowel 41.276mm
Mount plate 6.35mm
Spacer 25mm
Y
Frame plate 6mm
Chamber Surface
10
Result

• 4.411X 10Y 44.172
• If X0 (ME1/2 mount known perfectly)
• Need 4.42mm extra between DCOPS and ME1/3
  surface
• If Y0 (ME1/3 mount known perfectly)
• Need 9.00mm extra between ASPD PG4 and DCOPS
  center.

11
But

• Photographs show the ASPD mounting, and it
  matches my understanding from the CAD drawings
• Xiaofeng assures me he mounted the DCOPS directly
  under the mounting plate
• No room for 9mm spacers at ASPD
• Is the ASPD position wrong?
• No. Celso finds agreement between PG and his P4
  reference calculation
• And..

12
ASPD P4 to chamber surface

• ME1/2 has coded targets also
• Compare Cocoa 0T fit to coded target locations in
  Z
• Suggests ASPD to surface is understood and OK

13
Transfer Plate?

• Trying the same trick with the Transfer Plate
  suggests that the DCOPS center is 8.7mm farther
  to the rear than I calculate from drawings
  AFFLp-15.00.00BLK etc

14
This afternoon

• Redo model of line using PG points as reference
  instead of Link system references
• Note that some of the PG alignment pin
  measurements are inconsistent with each other.
• Fortunately we usually have the coded targets on
  the chamber surface to cross-reference with, and
  let us decide which to discard