Minutes of the Tracker Meeting
February 12, 2004
1. Grounding tube and tray assembly drawings
2. Bias circuit issues
3. Status of sidewall prepreg specs
4. Progress report on bottom tray and I/F drawings
5. MCM PRR results and status of actions needed to get materials to Teledyne for flight MCM fab.
6. Status of specs for tray bakeout
Ben reported on some tables of specifications agreed to with COI and YLA, for prepreg material, including some cost estimate. Ben had talked to COI this morning and also confirmed that COI WILL guarantee the mechanical properties quoted. Plyform now needs to put the info into their purchasing document. COI said that they would stand by these values for a buy from Italy. Ben will send the COI info alone to Nanda and Sandro. He emphasized that there is no ITAR problem to be concerned about. Test data generated by COI would be available to Plyform (but they would not tell Plyform exactly how they do the tests). We will get a clear status from Nanda next Thursday, including a date when the prepreg will be ordered.
Sandro wants to be sent the requirements for testing the laminate. Ben will write down a test matrix, which will be essentially what was done in the past, minus the conductivity and insert tests. Ben said that he had asked Plyform to redo their calculation of the modulus for their tensile test. Also he wants them to describe the failure modes of their test coupons using ASTM nomenclature. He is waiting for that information.
Ben said that he is satisfied with the Plyform face sheet prepreg spec and the ESPI method for evaluation of the sandwich.
Sandro reported that he and Jerry agreed on using Sandro’s method for the grounding tube assembly. Assembly drawings will be rev’ed to correct the grounding tube drawings. Jeff Tice will pass that by Mike Foss and will run down the action to revise the drawings and submit them again for sign-off.
Mike reported on several items:
1. In Pisa they spent time discussing the tower assembly fixture and concerns about the countersink screws negating the alignment initially achieved with pins. They concluded in belief that with the 120 screws the centering force is small and the tower will hold the initial alignment.
2. They discussed in detail the Ti parts drawings. Martin has been making small dimensional and tolerance changes. They also fixed the specifications and tolerances on the alignment holes used to position the inserts in closeouts. They also added a tapped hole in the corner brackets to hold a grounding wire, since the grounding tubes won’t work on the bottom tray (the M55J doesn’t conduct well enough).
3. They discussed assembly of flexures to brackets and indexing of the cone. They believe that if they can hold the tolerances specified on the Ti parts, then at 3 points the tower can be mounted on single concentric cones. This is the preferred integration strategy, to be replaced by all dual cones only if a Grid bay or bottom tray comes in out of tolerance.
4. Mike emphasized the need to send an engineer to the machine shop to go over the drawings and also to be present when they CMM the first articles.
5. Mike proposed for a repeat vibe test to put dual cones at all 12 places, to qualify that worst-case configuration.
6. Shipping containers: INFN will provide SLAC a sketch of what they want. The same also for the lifting fixture.
7. Thermal strap: INFN will redline the thermal strap drawings to reduce the risk of the mounting screw threads producing copper shavings. We also need to verify with Jack Goodman the need for RTV on them on the Tracker side in assembly.
Mike Foss need to mail pdf files of the completed prints for Martin to check on the way home.
The plan is to release drawings on Tuesday. It is urgent to get a PO in place, which requires a requote to the new drawings (the biggest change is the new requirement to assemble the flexures to corner brackets and drill the conical holes.
Martin expressed concern about the tight profile tolerances on the flexure blades and whether the shop could accept the drawings. In fact, those drawings were quoted to by Advanced Machining. Also, the same tolerances were in the drawings used by Continental Machining to make the EM flexures. (Later Erik reported that Continental Machining claimed to be within tolerance on the flexure profile requirements, according to their inspection reports, but the LAT did not do an independent verification.)
Mike and Martin discussed with Sandro the impact on Tower A if we do repeat vibe test with the new interface configuration. Robert emphasized that schedule exigencies may dictate using the second bottom tray for the vibration test (with the first going to Tower A). There was discussion of the Ti schedule. Robert said that Advanced Machining gave Tom Borden a verbal estimate of 4 weeks to get the first articles out. The 8 to 10 weeks estimate is for the entire flight lot.
We need to keep in mind, when finalizing the PO, the need for one extra set of parts for the EM tower and parts for joint qualification testing.
Sandro asked for confirmation that we will not do T/V cycles following the thermal-balance test. There seems to be agreement among everybody to strike the cycles from the test plan.
Sandro reported that the honeycomb will be at INFN tomorrow morning. Also, Pisa will deliver 7 MCMs to G&A tomorrow.
Sidewalls will go to Terni tomorrow for thermal testing.
Erik reported that the static test fixture is still in Los Alamos. There is snow, so he was skeptical that the truck would make the pickup (late-breaking news: it did get picked up).
Erik is putting together a report on how to do the static test. After that we will re-evaluate the need for Erik to travel to Italy to transfer knowledge of the test procedure.
Sandro needs to identify somebody in Italy who owns responsibility for the test. Mike also felt that we need to identify somebody at SLAC to take ownership of the test and the specifications.
Robert reported that the MCM PRR was a success on Tuesday at Teledyne. The onus is on SLAC to get the parts down there to start flight production next week, in which case Tower-A MCMs could be done and burned in by the end of March. The long poles are screening of the pitch adapters, testing of the PWB coupons for already machined boards and/or machining of boards from panels already tested, and receipt of new connectors from Omnetics.
We will meeting Friday at 8:00 by phone between SLAC and Pisa for an update.