Minutes of the Tracker
Meeting
Action Items:
Agenda:
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
8) A.O.B.
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