Minutes of the Tracker Technical Meeting
January 23, 2002
Tom reported that the last of the dummy detectors went onto the bottom tray yesterday. He will send all the trays as 3 separate shipments. Sandro said that he needs an e-mail specifying for each box what is inside.
Sandro said that he cannot get the sidewalls from Fed-Ex in Milan until Monday, which does not give them enough time to meet our original schedule. After getting them to Pisa they will need to machine some reference holes in the sidewalls. In the future we should ship by air freight to the Pisa airport, not by Fed-Ex. We need now to delay the test program in the U.S. We decided to move it out one week, with the shake test on February 19th and 20th and assembly starting on the 11th or 12th. The idea is to ship the assembled tracker directly to Albuquerque, so we discussed putting accelerometers in during the assembly testing at SLAC. Ossie offered to drive the tower to Albuquerque over the weekend. Tom will coordinate planning the accelerometer locations.
Tom initiated a discussion of planning on post-machining flight trays (some machining needs to be done on the current prototype trays to square them up, in any case). Several of us objected to the idea of cutting the carbon-carbon after tray assembly, and Robert asked why the prototype trays are not within specifications. Erik said that the locating pins in the tooling probably were not getting seated properly each time, as it had to be done by feel and was probably done by different technicians for each tray. Erik suggested changing the design to ensure that the pins get back to the correct location each time. There was also a discussion of using room temperature cure and the Plyform method of assembly. With a room-temperature cure the jig can be simpler, with the closeout parts pulled up against a flat steel surface. However, this requires the face sheets to be bonded onto the core first, at high temperature. Robert asked whether they can then ensure that the adhesive doesn’t get wiped off when inserting the closeout pieces. Erik expressed concern about the long time needed for complete cure (he worried that if the tray is removed before a complete cure is done, the carbon-carbon might still move). Sandro said that after the initial room-temperature cure in the jig, they remove the constraints and then accelerate the cure with a moderate temperature. There was some concern about twisting of trays. Ossie said that the existing trays generally have a small twist but only a very small force is needed to push them flat against a surface plate.
Tom said that he sent a map of the tray dimensions measured at SLAC to Sandro. He would like to talk Friday morning at 8:00 about tray assembly & tooling and will schedule a conference call.
Tom said that he received inputs from Sandro & Erik about the engineering model parts list. He will sit with Ossie & Dave Nelson and fill out the rest of the schedule for the parts.
Robert fretted about the engineering model schedule. Sandro is predicting March 11 for delivery of face sheets and inserts, so tray assembly cannot start until then. Putting that into the schedule (which is tight throughout) moves the CDR date to early August. But it does give a little more time to finalize details of the closeout design before doing the machining. Robert requested an estimate from GMSI (via Erik) on how long it will take to machine half of the tower closeouts and how long to get into their queue. Erik said that we should give GMSI about 4 weeks. Erik asked how the inserts will be installed. Sandro said that Plyform has a tool similar to the original Hytec design. Tom asked him to send the drawings or post them on the web. Sandro said that they are still working on details of where to put the alignment pin holes into the closeouts, since the existing ones end up too close to the edge of the tower sidewalls.
Tom concluded that we should get the closeout drawings finalized by Feb. 15, while Sandro is in California. He also said that SLAC procurement needs to know when the closeout material will arrive, as they are getting upset over the delays. Erik will talk to Allcomp.