Minutes of the Tracker Technical Meeting

December 20, 2000

 

Eduardo reminded us  that there will be a database discussion at the software meeting.  Ronaldo said that Luca and Nick should be present.  They agreed that Luca will give a presentation.  Luca will talk to Sandro and Ronaldo about items to put into the database.  Eduardo will talk to Masa and Luca about planning.  Eduardo is primarily interested at this point in high-level discussion about uniform handling of data across institutional boundaries and so forth.

 

Ronaldo said that Luca and Gloria will modify their existing database to use for tests on the 10 HPK wafers just now arriving.  Hartmut asked if the database is compatible with Excel?  That answer was no, but it is made up of web pages.

 

Gwelen spoke about work on the MCM board (see the attached drawing from BJ).  He found that it is possible to make a layout that follows IPC rules on the pitch adapter.  We can keep 100um traces and spaces.  Also, we can make it with no turning of traces in the bend region.  To do this, he centers chips on the corresponding set of detector strips.  It is possible to do that now because of a change made this week in the readout chip design.  Logic was added to make the two chips at the right and left ends of the readout chain send their data and trigger out via pads along the back edge of the chips, instead of at the ends.  This means that no wire bonds are needed at the very ends of the MCM.  Gwelen and BJ also tentatively changed the 1mm screws to 1.6 mm screws.  Dave Nelson will see if that is compatible with the layout.  Most likely it will not work and we will go back to 1 mm screws.  BJ moved the connectors according to the recent change in cable placement.  He also removed 2 screws. 

 

Tom asked how we will make the electrical connection from MCM ground to closeout.  Erik said that he recently drilled and tapped the carbon-carbon material.  The results looked good.  Has not yet tested the torque needed to strip out the threads.

 

Tom said that Christek supplied some price estimates.  Metal bodied parts .086 thick would be in the $70 range.  Gwelen suggested that we also talk to Nanonics about metal-bodied connectors.  Tom will contact Nanonics and will also compare the two brands to see if they can use the same PC board decal.

 

Erik asked if the new MCM board accommodates 4.2 mm wide corner posts.  Yes, said BJ, with 0.6 mm clearance on each side.

 

Steve warned us to be careful not to mix up closeout pieces between thick and thin converter trays.  Tom said that we need to mark them clearly somehow. 

 

Erik asked if it would be possible to have an even number of screws across the MCM, to keep screws away from the board center.  He said that Hytec is probably about a month away from machining an actual closeout, so there still is time to play with the details.  A decision was made to go now from 7 to 6 screws.  It is important to place screws near to gaps between chips in order not to congest the top layer routing.  The grounding screw should be kept away from center also, as is the case already.

 

Tom reported that he and Robert reworked the schedule to the point that they believe it should now be stable to WBS level 6.  We will report to SLAC/DOE to this level.  It is posted on the FTP site (scipp.ucsc.edu, anonymous login, cd to pub/johnson).  The 98 versions doesn’t have the WBS numbers.  Ronaldo said that Pisa has installed MS Project 2000.  They will work on details at level 7 and 8 and also check that level 6 looks okay. 

Tom reported that he also is rearranging the Excel budget.  He will reallocate the non-INFN funds to items that California and Japan are responsible for.  Pisa would like to receive a revised budget by mid January.  Pisa will provide costs for the INFN components of the budget.

 

We have decided to continue to work Tracker schedules and budgets in MS Project and MS Excel.  After rolling it all up to level 6 we will feed the numbers to the PMS at SLAC whenever required.

 

There was a discussion of dummy detector procurement for the engineering model.  We will need 500 to 600 pieces.  Hartmut said that HPK dummies are about $105 each.  They could be bought in Japan (but Japan has no funds allocated for that), by SLAC, or by INFN.  Ronaldo said that HPK rejects could be bought in Italy, but we should not assume that INFN will pay for them all.  He would like the costs divided in a similar way to the flight towers. Guido warned that there is a danger of small rate of funds in 2001.  They need to leave money for GLAST work with the local industry as much as possible.  Robert said that he didn’t believe that on the time scale of making the EM ladders there would be enough HPK rejects for the whole EM.  Therefore, we need to plan to use blanks for a significant part of the EM tracker. Micron blanks run about $50, while SLAC blanks run $60 each.   SLAC is now buying 100 blanks.  Pisa will work out the ladder production schedule for the EM.  Robert said that it might be as early as spring 2001, Pisa can best judge when they will have a ladder assembly line ready to go.  Probably will be early and we will take as many rejects as available.  Robert suggested that we figure out the funding of blanks and rejects in late January after budget and funding are more clear.

 

Sandro reported that they have made the 1st ladders with Si blanks.  The alignment looks good (15 um).  Planarity is not so good, so they will improve the machining of the fixture.  They have some problems with gluing, in particular controlling the glue application.  Eduardo will send a note with step-by-step details on their gluing procedure.

They started fabrication of ladder production tools with 3 industrial partners.  All will start immediately to make tools and fixtures, to be ready in February.  Then they will assemble ladders from Si blanks, including wire bonding and encapsulation.  After that they will select the vendor(s) for production.  They are getting good costs estimates for the gluing, wire bonding, encapsulation, and measurement.  The numbers are consistent between all the vendors.

 

Erik reported that the Hytec focus has been on panel-assembly tooling.  PCI has all the material for laying up face sheets.  However, the cutting to size depends on the assembly procedures, so it is urgent to get that nailed down.  Erik thinks that they are getting close.  Their plan is to get the drawings to PCI by end of the week.  They received test data this morning for mechanical tests on the side-panel material.  The modulus looks good.  The P30 carbon-carbon had about ½ the ultimate strength of the other graphite-reinforced epoxy panel.  They are still waiting on thermal test data (which probably is the primary driver, aside from cost).  The P30 was looking better for cost.  They also got started on pullout tests for sidewall fasteners.  They also delivered the simplified model to Martin of a tracker tower and already got some feedback from SLAC.  There was a Hytec/SLAC meeting yesterday about how to proceed.  SLAC will feed reaction forces back to Hytec, which will allow Hytec to finalize the tower design.

 

Robert brought up the issue of vertical alignment.  The problem is that the countersunk screw holes in the tower walls will attempt to drive the alignment, in addition to the tray corner posts and spacers.  This is an old issue that does not appear to be completely resolved.  Tom and Erik will discuss this offline.

 

Sandro said that they would like to come to Hytec in the 4th week of January (the 22 or 29).  They will decide for sure in the 2nd week of January.  Either of those days looked okay for Hytec.

 

The next Tracker telecon will be January 3.

 

Decisions:

1.     Use only 6 (rather than 7) screws across the length of the MCM (plus the screws near the connectors).

2.     Report the Tracker schedules and costs to the project only to WBS level 6.

3.     Use MS Project 2000 and MS Excel for tracking of schedules and costs at a more detailed level within the Tracker group.

4.     Procurement of dummy wafers and rejects for the mechanical engineering model.

 

Issues:

1.     Screw size for MCM attachment (1 mm vs 1.6 mm).

2.     Metal body vs plastic body connectors.

3.     Clear marking of different closeout types.

4.     How to control vertical alignment with countersunk screws.

 

Action Items:

1.     Luca: prepare a presentation on Tracker databases for the software meeting.

2.     Tom: contact Nanonics and investigate the compatibility of connectors from Nanonics vs Christek.

3.     Pisa: check the schedule at level 6 and work on details within their areas of responsibility at levels 7 and 8.