Minutes of the February 17 Tracker Meeting



            1) MRB (see the table of NCRs below)

            2) MCM inventory for Tower 3

            3) Status Towers B,1,2

            4) A.O.B.


 NCRs 283,377,399,400: these MCMs all exceed the documented requirement for maximum number of dead channels per layer.  The disposition agreed upon is to use them as is.  See the 1st February 17 presentation on http://glast.pi.infn.it/GLASTtalks.html#MRB.


NCR 385: A resistor got damaged on one MCM mounted on a tray.  See the 1st February 17 presentation on http://glast.pi.infn.it/GLASTtalks.html#MRB.  SLAC needs to send resistors to Pisa for rework.  Albert will bring some back from Teledyne tomorrow.  These are the 680k resistors.  Jeff will send them to Pisa in a Fed-Ex envelope.  Pisa will write a procedure for the rework and send it around for approval.  Nusil will probably be used to cover the new resistor, in place of the usual conformal coating.


NCR 372: See the 2nd February 17 presentation on http://glast.pi.infn.it/GLASTtalks.html#MRB.  The meeting agreed with the proposed disposition and corrective action.  There was an open action for John Ku to close with Andrea on exact pass-fail criteria.  Also, Andrea will review with Arthur the procedure for dithering in the last cones.


Comments received by email from John Ku in connection with NCR 372:

1) The proposed pass/fail criteria is okay for me.  Based on observed performance of the bottom tray joints, we can derive acceptable limits based on statistical reduction of data.  I have discussed this in the past in detail with Andrea Tenze and we are in agreement.  This new pass/fail criteria removes the somewhat more ambiguous torque loss limit and verifies performance in a more realistic way. 

2) We looked at the M4x6mm screws together last week and agreed that it provides adequate engagement into the closeouts (no less than the other M4x6mm screws).  Additionally, it has successfully passed environmental testing.  Due to these two factors, I believe it have been verified by test and no additional analysis is needed at this point.  In the future, if there are other substitutions, we should be alerted at or before the TRR so the relative risk can be evaluated.


NCR 374: Riccardo checked during assembly of the sidewalls onto the tower that there was no problem with alignment of the holes between sidewalls and tray, so this closes out all issues associated with this NCR.


MCM inventory: SN 1062 worked at SLAC but initially a GTRC was not working in Pisa.  It works now with the hard reset applied after power-on.  That makes 2 tall MCMs in Italy available for Tower-3.  SLAC has 3 tall MCMs in transit to Italy, along with 15 short MCMs and 2 NCR-226 tall MCMs.  Robert will send a complete list of these to Pisa.  There are 6 rejected MCMs at Pisa from G&A.  Sandro is looking into how they can be salvaged by rework.


Tower-1 status: the CPT on Tower 1 was done yesterday prior to sidewall installation.  It was performed with different test station than was used previously.  The power supply was set to 1 amp compliance (normally 3 amps in previous tests).  The 1 amp limit was not enough; they need at least 1.5 amp.  Luca wanted to make sure this was as expected?  Robert will ask experts at SLAC.  (The answer is that > 1 amp is needed in order to supply sufficient surge current at power-on.  SLAC sets the compliance at 3 amps.)


Tower 1 CPT looks good.  There is a link to the results on the Pisa main web page.  Alignment was in progress, and we heard during the meeting that it passed.


Tower 2 trays are still on track at G&A for completion by next Tuesday.  Sandro is at Plyform to verify WIP, including sidewalls. 


Dave gave a reminder that Kapton tape needs to be installed in Pisa on flex cables for Towers 1 and 2.  He is trying to get the procedures in place for this to be done at SLAC starting, hopefully, with Tower 3.



                                                TOWER”1” NCR’s STATUS – 15/02/05


NCR                 ITEM                                        TITLE                                        LAST  DISPOSITION                STATUS


283 Maj             Mid       063                     18 disconn. ch.                                              Refer to MRB                 Open


377 Maj             Top        006                    17 disconn.ch.                                               Refer to MRB                 Open


399 Maj             Bottom   005                     19 disconn. ch.                                              Refer to MRB                 Open


400 Maj             Heavy   015                      22 disconn. ch.                                              Refer to MRB                 Open


372 Maj             Bottom    005                    nut torque loss                                                Refer to MRB                 Open


374 Maj             Bottom    005                    Dimensions out of spec.             A) Use As Is for Tower “1”                        Open

                                                                                                               B)  verify no problem at Tower level  


Other (Tower -“2”)


385 Maj             Mid       070                      GTFE not working                               Refer to MRB                Open

                                                            (Resistor R111 broken)