Gantry meeting

1
FNAL Gantry

• We have built 49 TOB modules with full flex
  hybrids.
• 2 were built early on with Araldite instead of
  RTV12
• In some cases we had problems with the pattern
  recognition or the after cure program and needed
  to determine the final alignment data with an
  optical inspection machine. In a couple of cases
  we have noticed large movements of sensors during
  the curing phase. The reason for this is not
  completely understood.
• The most recent 17 modules constitute our
  mini-production set.
• The following plots were created to emphasize
  metrological features of our Gantry for this
  reason problem cases have been excluded from the
  data set.
• Note that the X and Y values are taken from the
  left points (1 and 3).

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FNAL Gantry
X Xnom(m)
Y Ynom(m)
Full data set
3
FNAL Gantry
X Xnom(m)
Y Ynom(m)
Last 17 modules
4
FNAL Gantry
Sensor rot. angle (mdeg) Full set
Sensor rot. angle (mdeg) Last 17 modules
5
FNAL Gantry
Delta_X (m) Full set
Delta_X (m) Last 17
6
FNAL Gantry
X-Xnom(m) Position 1 Full set
X-Xnom(m) Position 2 Full set
7
FNAL Gantry

• Conclusions
• There are clear differences between the X and Y
  placement accuracies and differences between
  module positions and these probably all have the
  same root cause (large Gantry Y 2D corrections).
• Our sensor placement accuracy relative to the
  existing acceptance cuts is probably okay we
  would not be in favor of tightening them at this
  point. A larger concern would be to avoid
  accidents (MMI problems, vacuum leaks, etc.).
• In keeping with the original design our hybrids
  are not held in place initially with vacuum. The
  existing acceptance cuts, particularly the 30
  mdeg angular tolerance, are too restrictive.
• We have been accepting all hybrid placements
  where we are able to complete the sensor-to-PA
  bonding.

8
FNAL Gantry

• MMI repeat command problem
• When we first activated our 2D correction file we
  noticed a phenomenon where the Gantry would
  repeat lines in output files and sometimes behave
  erratically.
• The problem usually begins as a file I/O failure
  but ultimately manifests itself as a random
  repetition of MMI commands.
• There is some evidence that there is a positional
  dependence to the problem In our case we almost
  always encounter the problem when we measure the
  second fiducial on the third hybrid. This leads
  to problems with the output files and the XML
  file must be corrected or created from scratch.
• Because of this problem we have been restricting
  ourselves to 2 modules per assembly plate. Since
  we have 6 assembly plates this is not seen as a
  limitation, at least in the near term.
• Gabriella had originally brought this problem to
  Aerotechs attention several months ago and they
  now claim that they at least understand the
  problem. Until we receive and verify a solution,
  however, this remains a concern.

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FNAL Gantry

• Other issues
• We have recently received TOB stereo CF frames
  and PAs and have started to pursue a dual
  strategy of modifying the code for the existing
  assembly plates and also building rotated
  plates based on a design prepared at UCSB (see
  next slide).
• We have several thousand syringe tubes from the
  original order but are running low on needles and
  pistons?!
• Aerotech has quoted us prices on a spare U-motor
  and amplifiers and we need to follow up on this
  issue with our Santa Barbara colleagues.

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FNAL Gantry