Minutes of the Tracker Technical
Meeting
August 7, 2002
Action Items:
1. Luisella: review the drawings
from SLAC asap.
Tray panels: Plyform is waiting for
the new set of tooling. At present
there still are only 4 trays built, plus the tray with intentional
defects. An very high frequency
ultrasound system in France was able to see the defects. Now they will try the same with an
interferometric system. Plyform is
closing for 3 weeks. They will start up
again August 26. Luisella will return
August 19 and will finalize the tungsten and kapton assembly systems. Sandro thinks they will be ready the second
week of September. She will also check
the top/bottom fixture drawings from SLAC, which will be time critical by that
point.
Ossie expressed some concern about
the effect of water on the tray in the ultrasound tests. The tests cannot be done in air because that
gives too large an impedance mismatch.
Sandro in principle prefers the interferometric system, which can give
more information and doesn’t require dipping in liquid.
Tom reported that Hytec will image
damaged areas of the bottom tray with their 3-D x-ray system. They are also cutting off a sample of
carbon-carbon material to send to GSFC for analysis.
Tom spoke with Teledyne. They verified that they can wire bond on
boards from Young Electronics. Two
non-functional MCMs will be ready early to mid next week. Robert and Tom will travel to Teledyne
August 15 to review progress.
Sandro went to G&A on
Monday. He sent to us data on ladders without
encapsulation (see LAT-TD-879 and LAT-TD-880).
They find excellent alignment.
Depletion voltage looks good; they sorted wafers by depletion voltage
for assembly to make the ladders uniform.
There was no change after assembly.
Leakage current increased higher than in prior tests, by a factor of 1.8
on average. This factor is the worst in
the first ladders, for which the worst wafers were used. One ladder had 10uA. They inspected and found a dot sitting
between guard and bias rings. They
removed it with alcohol and the current went down to 3uA. G&A thinks the wafers are quite
dirty. Dust is coming from the
cardboard foils in the envelopes. The
INFN groups will have to clean the wafers for G&A. They did AC tests on 20 ladders, with a 100V
step. They found 4 additional broken
caps, beyond the HPK known bad strips.
G&A now is waiting to get back clean wafers.
Tom said that they had a successful
discussion in Los Alamos of the modeling effort. They came up with a plan to complete the analysis. Tim Thurston will write up a report. Tom is also working together with Martin's
group on the attachment of the flexures to the Grid.