Minutes of the Tracker
Technical Meeting
August 1, 2002
This meeting was held
Thursday morning, rather than Wednesday, because of a conflict with the
delta-PDR review in progress at SLAC.
Sandro presented the status
of ladder production at G&A: 40
live ladders are glued together and have been measured. They are wire bonding now. Sandro has the fin results from metrology:
3.5 micron rms error, with a maximum error of 15 microns. The bond thickness ranges from 7 microns to
60 microns with a 31 micron mean. Most
are in the range from 20 microns to 40 microns. See the attached histograms.
They have tested bonded 20
ladders electrically. 5 strips are bad
that were not already declared bad by HPK.
They look like broken caps. This
is a 0.065% rate.
The bad news is that there
is one ladder with very high leakage current.
It starts to discharge at 50V and reaches 10uA at 200V. A second ladder goes from 550nA for the sum
of 4 SSDs before assembly to 1.6uA after assembly. They will check individual channels on these two ladders to try
to isolate the problem. The other
ladders increase more in leakage current than expected, based on earlier
testing. Typically the current is
doubled. INFN workers are at G&A
today and tomorrow checking the system for possible problems to explain the
anomalous current. See the attached
plots.
They plan to encapsulate
the ladders starting August 26, as G&A will close next week. Sandro will probably be away on vacation Aug
9 to Sept 2 but will finalize plans this week.
Luisella and Ricardo will be available last 2 weeks of August.
Top/Bottom tray material:
it should arrive at SLAC from Alcomp by August 20 (earlier for the top
tray). Tom needs to call to check on
this.
Top/Bottom tray panel
assembly tooling: BJ will post the
drawings. There are 2 pieces that must
be different for the bottom tray, with respect to the top. They need to be reviewed quickly by Luisella
when she returns the 19th Aug. They
will take about 3 weeks to build. SLAC
will QC the tool before shipping.
Sandro said to measure the tool after assembly, as they found some
surprises there in the standard tray tooling.
SLAC should ship by 16 September.
Mid-tray panel
assembly: only 4 trays panels have been
made so far, as they have been working on correcting the tooling. Real production will start August 26 at a
rate of 2 trays/day.
Assembly of tungsten onto
panels: This will go parallel with
panel assembly. The first week of
October the trays should be finished with Tungsten & Kapton. 2 weeks are required to glue ladders, plus
one week to wire bond.
Fabrication of the Kapton
assembly tool: The tooling has been
ordered for both tungsten & Kapton.
Order of extra connectors:
in progress. Robert and Dave are
working on ordering more for the test systems and burn-in system.
Fixture for wirebonding
trays: Sandro said that a mockup tray is at G&A, along with the electronics
mockup. They are working on the fixture
for the Delvotec 6400 wire bonder, which has a moving head. The jig will position the tray in 4
positions to wire-bond 1 ladder at a time.
Sidewall machining: Tom
will schedule this. It is needed in
October.
Tower lifting fixture:
design is in progress. There will be an
adjustable one and a simple one. The
adjustable one is for installing towers into the grid. A 3rd fixture with fiducials (tooling balls)
is being designed for measuring alignment.
The simple fixture is sufficient for the EM.
Tower assembly fixture:
SLAC is studying the issue of how to attach flexures to the module with
adequate alignment. The idea is to make
the needed fixture part of the tower assembly fixture. For that they need more space at the bottom. Hence they will raise the support walls
about 5cm. They are refining the design
with Nordby et al. The goal is to have
drawings for Luisella when she returns.
Thermal gasket redesign:
there was some discussion yesterday and will be some discussion with NASA
today. Some test data from Jeff Tice on
samples is in hand. One issue is whether
to mount the gasket to the Grid or the Tracker. Another is whether to put adhesive on one side or both sides.
Flexure-mount analysis
& redesign: Analysis is in progress at Hytec. Tom will be in Los Alamos next week with ART members for
discussions of the model.
Sandro reported that
Ricardo is working on ultrasonic testing of trays at a company in France. They have high enough frequency to detect
the thin facesheet. Another sonic
system is being investigated near Rome, with stimulus from tapping rather than
transfer of energy from the air. A
third is an interferometric system in Frascati, similar to the Hytec
system. It detects movement of the
parts in a thermal cycle.
Tom said that we need to
start working on flight procurement of tungsten foils.
Also, the closeout material
PO has been let to Alcomp, with the first lot to be delivered in late December.