Minutes of the Tracker Meeting
1) Tower A vibe test progress
2) Env test action items
3) Solithane issue
4) EMI shielding
5) Tower B tray status, materials, shipping container, & expected schedule
6) Pre-ship review for Tower A
7) Tower A EIDP
Tower-A status: it was
safely transported from
The vibe test action items were reviewed. We discussed the cable clip NCR, concerning the screw that could not be inserted because of interference with the cable. John Ku had been working on other priorities and had not yet done any analysis of this. Dave will check with John on the issue after the meeting. The general feeling was that this was a very small risk. The NCR remains open but the test can proceed.
Nicola said that there is an
updated procedure on
Robert will pull the drafts from the web and send them to Natalie to send out for approval.
EMI shielding: Martin presented some information on the scheme he has been working out to tape the top and sides of the tower for EMI shielding. For the top, first one lays down a big square of aluminum foil on the top tray. It has to be painted black over most of its area. This step could be done at tray fab or on the assembled tower. Also, the foil could be painted before application. He has developed a process to put down the foil without crinkling it, so the paint would not get cracked. Martin is writing a procedure and will do a prototype test today or tomorrow. After the top black piece, then one lays pieces around the perimeter of the top tray, with the goal of joining the outer sidewall aluminum to the aluminum on the top of the tray. The tape has a conductive adhesive, but that adhesive must contact aluminum, not black paint. That is why the tower sidewalls are not painted all the way to the edge. Similarly, the aluminum on the top tray is not painted all the way to the edge. Furthermore, because of the tight clearance between towers, we cannot have a double layer of tape anywhere around the perimeter. The only thing that does not get covered by the tape are the reflector ball nests; we will cover those at SLAC after the LAT alignment is completed. Martin wants to try out this procedure on the EM tower at SLAC if possible. Also, of course, we need to tape the 4 corners of the tower. There will be no tape at the tower bottom. The tower bottom has too many things in the way, including 12 flexures, 4 thermal straps, and 8 cables. Also, the biggest noise source is probably the TEM, which can radiate past the calorimeter and out the gap at the tower bottom. If measurements show this contribution to be too large, then it may be necessary to block it from flowing out the gaps between towers. That will be a LAT level project, however, not a single tower issue.
Riccardo asked if in the scheme the lifting device will still work. Martin said yes, we will cut through the foil where the M4 bolts go.
Riccardo proposed an alternative scheme in which a carbon fiber panel with aluminum on both sides is attached to the top rim of the top tray (and also another possibly attached to the bottom tray). Robert said that since this would interfere with the lifting fixture, it would have to be installed after the towers are on the Grid, making it difficult to install and tape the corners.
Robert suggested that given
the time needed to prototype the procedure at SLAC, there will not be time to
execute the procedure on Tower A in
Solithane issue: INFN
Tower B status: the trays will be done at G&A before Christmas. Alenia is closed until the 2nd Monday of January. Jeff will expedite getting the shipping container to SLAC (it is ready to ship), in order to get it out of SLAC before the 18th. In that case he can get it to INFN right before Christmas. Steve says that an inner container will be ready and can go with it. Jeff said that he will ship materials for Tower 1 and 2 next week and will include more brackets. Emilio will send information on anything else needed.
The Tower A pre-ship review should take place between Christmas and New Years. We tentatively decided on Dec 28. We will need a completed CPT done following T/V before then, and several NCRs need to be closed. The EIDP should be mostly ready (just missing the parts that will have to be filled in at SLAC after shipping). We agreed to work on preparations for the review next Thursday and possibly also on the 22nd, after completion of the T/V test.
Tower 0 heavy tray
temperature cycles will start Monday in