Minutes of the October 9,
2002 Tracker technical meeting
Agenda:
1. EM schedule
- bare trays
- trays with W and Kapton
- EM mechanical MCMs
- EM working MCMs
- Mounting MCMs
- Mounting ladders
- Final wire bonds
- Electronic and environmental testing of trays
2. EM test station for Pisa
3. Luca's trip to SLAC
4. 50 vs 300 ladders at
G&A
5. A.O.B.
Action Items:
- Ossie: make sure the the
CMM is available for the new tools.
- Tom: find out from GSFC
why the GE615 RTV cannot be used.
- Tom: check on why Nusil
cannot ship the conductive glue for ladder attachment.
- Sandro: check whether
enough tungsten is in hand for the EM tower.
- Tom: give connector savers
to Dave for the Pisa test system.
- Luca: send Tom a list of
organizations in Italy that may use LAT test software.
- Sandro: find costs for
obtaining thin tungsten in Europe for flight production.
The top tray insert
installation fixture and assembly fixture should arrive at SLAC next week. Ossie should schedule use of the CMM at SLAC
to QC them before shipping to Italy.
Production of tray panels
will restart tomorrow in Plyform, following repairs of the equipment. They expect to be able to assemble at a rate
of 3 trays/week starting next week.
Sandro predicted a finish data of Nov 8 for all but the bottom tray.
Pisa measured the tungsten
assembly tool. It needs slight
modifications for glue clearance.
Sandro expects it to be done in about 1 week, so they can start gluing
tungsten in week 43.
The Kapton assembly tool was
due yesterday. Sandro needs to check on
the status.
Sando says that Plyform
should finish all of their work on the EM trays by the end of November.
In parallel, during November
they can start placing ladders on trays.
Tom will talk to GSFC about
why we cannot devolatize the GE615 RTV adhesive prior to use.
G&A can start making
ladders without encapsulation, with testing done after wire bonding. It was agreed to allow G&A to start on
this.
Pisa has a problem obtaining
the Nusil glue for ladder attachment.
Tom will check on this. Sandro
will forward the message that he received from Nusil.
Tom will meet with Teledyne
tomorrow to discuss the MCM assembly progress.
Dave is making a test
connector for verifying the mechanical/thermal MCMs when they come off the line
at Teledyne.
Sandro said that development
of integration procedures for attaching the MCM to the SSD ladders is on hold
because of conflicting ladder activity at G&A needed to develop procedures
for the new encapsulant.
There was a meeting with
Parlex meeting yesterday. The EM
readout cables will be finished in a week or two. Tom gave Parlex enough connectors to populate one complete set. Robert has 110 connectors on order. The mini tower needs 4 cables, but only one
or two Nanonics connectors on each.
Sandro will check if they
enough tungsten in Pisa for the EM. The
mini working tower has only thin tungsten on the top tray. Some more thin tungsten is on order (it was
ordered in case it would be needed for the 3 bottom trays).
Tom will give Dave 2
connector savers so that he can finish the enclosure for the interface board to
be sent to Pisa. UCSC assembled and
tested a mini-MCM that will be shipped to Pisa in a day or two.
Tom said that ITAR needs a
list of organizations in Italy, including vendors, that will use LAT
software. This could be an issue if we
make use of the spacecraft vendor software.
Luca will send a list of organization names.
Robert suggested that we use
an existing bottom tray and sidewalls to test tower assembly, since the new
bottom tray will be late. Tom said we
will have to work around a schedule conflict with bottom tray test work.
Erik said that Hytec is
concerned about the tower displacement with the general GEVS input random vibe
spectrum. The PDR analysis was done
with the Delta-II spectrum and also assumed some support from a polymeric
gasket between tower and grid. With the
new spectrum, which doubles the power around the first lateral resonance, Erik
estimates displacements of 400 microns rms, which is too much. He reckons that we need to go up from 100 Hz
to about 130 Hz. To do so, they may
redesign flexures as single-pieces with blades further apart (8 mm?). But then we must also consider what this
does to the loads from increased lateral stiffness.
Tom said that there is a
troubling issue with the magnetic properties of the invar. The problem is not the ACD PMTs but with the
ACS and associated magnetometer on the spacecraft. It can tolerate only a few percent of the Earth's magnetic
field. Current estimates are 20% to 25%
from invar bottom trays. This could be
minimized by heating the invar above the curie point before assembly, to
eliminate permanent magnetization, but that would still leave a risk of it getting
magnetized again after assembly. SLAC
is purchasing some invar to make several mockup closeout frames to test.
There was a discussion of
the thin tungsten size and tolerance.
Present EM material is 5 mils thick.
For flight it will be 4 mils.
Sandro will look into cost and tolerance available for thin tungsten in
Europe. In the U.S. we can obtain the
foils for $14 each to 10 mils (1/4 mm) tolerance. More precise cutting by EDM would cost $7 more. Tom will send a spread sheet to Sandro on
this. We believe that the 10 mil
tolerance is fine and consistent with Tracker requirements. The squares would be cut 9 mils smaller in
size to keep within the maximum allowed by the tooling.
Luca said that the SSD
database is available from the Pisa web site.
There are two reports: Pisa tests and HPK tests. There is also a facility to make one's own
analysis. Download the MS Access
datafile and an executable file and select the analysis. He will do a similar thing for ladders. Robert said that he has a student starting
to work on a database for the ASICs and MCMs.
He would like to follow the Pisa example. Luca said that he can offer some advice when he is at SLAC.