TKR Tower Assembly PRR

1
GLAST LAT Tracker Tower-4/5 Pre-Ship Review
Luca.latronico_at_pi.infn.it INFN-Pisa
2
Tower 4 - Assembly and test highlights

• Apr. 13-14, 2005 (INFN-Pisa)
• assembly of complete tray stack
• incomplete cable set (C0,C1,C3,C5,C7) due to late
  arrival of complete set
• CPT could not be performed w/o cables C2, C4, C6
  due to a known issue with GTFE reset (see
  NCR/INFN/PI-417)
• Apr. 18-21, 2005 (INFN-Pisa)
• Installation of late cables
• Tray01 (L020) damaged during cable assembly -
  L023 installed in place of L020 (NCR/INFN/PI-470)
• CPT
• Sidewalls and alignment
• Final CPT and ship to Roma
• Apr. 27, 2005 (Alenia-Roma)
• VIB test
• May. 23-27, 2005 (Alenia-Roma)
• TVAC test with tower 5
• May 30, 2005 (Roma)
• Through customs in Roma airport
• Full EIDP details at
• http//glast.pi.infn.it (soon available)

3
Tower 4 - Assembly and components details
Tower PN LAT-DS-00722 (rev3) Tower SN 4
4
Tower 4 5 - Configuration

• Configuration
• Kapton tape and foam applied on the flex cables
  as per LAT-DS-00722
• 4 layers of Poron foam 0.037 THK used on Bottom
  and Top Tray (X) side (in place of 5 layers)
• Base Plate assembly
• Torque of nuts 5.1 Nm on TWR 4
• Torque of nuts 5.3 Nm on TWR 5, spec is (5.08
  0.56/-0 Nm) ? higher resonance frequency
  detected at VIBE test

5
Tower 4 5 Alignment, CG MASS

• Tower 4 and 5 well aligned and inside stayclear
• Mass and CG near estimated values (when used real
  masses)
• Data available on INFN-PISA web site

6
Tower 4 Open NCRs

• INFN/PI-494 Bad channels out of spec
• with reference to tray NCRs 460,465,464, 463 (all
  closed as per MRB) layers X6, Y5, Y3, Y13 fail
  test TE301 as expected and due to known problems
• Status of channels was monitored through TVAC
  test and show no significant loss of channels
  (see next slide), the NCR can be closed and
  converted into a SLAC one for reference.
• INFN/PI-496 Vacuum level out of specification.
• Common to Tower 5, see following slides.
• INFN/PI-503 CPT reduction after TVAC
• Common to Tower 5, see following slides

7
130 disconnected channels overall (less than
0.25). Layer X6 is stable as bad channels are
due to broken PA traces Fluctuations in layers
Y3 (H17-back-MCM 1117) and Y5 (H16-back-MCM 1049)
are due to delaminations in the MCM encapsulant
such MCMs were out of spec (gt20 bad chans)
already at SLAC and their use was authorized by
an MRB for schedule reasons
8
Tower 4 - Efficiency

• 3 layers with efficiency lt 99 as a consequence
  of missing channels (see previous slide)
• overall efficiency (pre-ship) at the tower level
  is 99.7 (required 98)

9
Tower 5 - Assembly and test highlights

• May 5-9, 2005 (INFN-Pisa)
• assembly (tray stack, cables, sidewalls,
  alignment, turn-over)
• test (CPT)
• May. 23-27, 2005 (Alenia-Roma)
• TVAC test with tower 4
• VIB test
• May 30, 2005 (Roma)
• Through customs in Roma airport
• Full EIDP details at
• http//glast.pi.infn.it (soon available)

10
Tower 5 - Assembly and components details
Tower PN LAT-DS-00722 (rev3) Tower SN 5
11
Tower 5 Open NCRs

• INFN/PI-492 Bad channels out of spec
• 18 bad channels found in Pisa on X2 (9 dead, 9
  disconnected)
• 7 dead were known from ladders
• nb of dead channels was stably 7 during TVAC a
  fluctuation in the Pisa measurement determined
  the 9 dead channels initially recorded
• Status of channels was monitored through TVAC
  test and show no loss of channels (see next
  slide), the NCR can be closed.
• INFN/PI-496 Vacuum level out of specification.
• Common to Tower 4, see following slides.
• INFN/PI-504 CPT reduction after TVAC
• Common to Tower 5, see following slides

12

• 45 disconnected channels overall (0.08).
• All layers within specs, i.e. nb of bad chans
  lt16, and stable
• new MCM encapsulant deposition, new MCM-PA gluing
  fixture, new shipping box are working!

13
Tower 5 - Efficiency

• worst layer is 99.4
• overall efficiency (pre-ship) is 99.7

14
EGSE/TVAC Communication problems with 2 towers

• Relevant NCR
• INFN/PI-474
• Problem
• Some instabilities in the EGSE systems for TVAC
  made it impossible to operate towers 1 and 3
  during TVAC test, and the EGSE systems had to be
  operated independently
• Action taken (as per dispositions)
• TVAC chamber setup was improved by using separate
  feed-through for EGSE-power lines and chamber
  temperature control
• GASU cables connecting to the TEMs were shielded
• Findings
• TVAC test of towers 4 and 5 was run with 2
  systems in parallel, the NCR can be closed

15
Tower 4 and 5 Vacuum level out of spec

• Relevant NCR
• INFN/PI-458, INFN/PI-459
• Description
• The vacuum level was mostly outspec during the
  test (specs call for 5E-5 torr)
• Observations (see annex for details)
• P 3.15E-5 torr at room T after 90 hours of
  pumping
• correlation between T-P
• no improvement after hot soak as observed with
  towers 1 and 3
• new material (MLI) that did not undergo bake-out
  was introduced for thermal blanket of tower 4 and
  EGSE RF shield
• The proposed disposition is use as is.

16
CPT reduction for TVAC

• Reference NCR
• 503 and 504
• Description
• TE101 (leakage current and power consumption
  test) not performed after towers 4 and 5 TVAC
  test
• Proposed dispositions
• only perform test TE101 after TVAC is anomalies
  are detected in the tower CPT suite
• Rationale correct behaviour of tower during and
  after TVAC is assessed by observations of layers
  noise, channels status, CR detection efficiency
• reduce CR data taking time to 100k events for CPT
  and 50K for LPT
• Rationale such statistics are enough for
  efficiency measurements and the test time
  reduction allow compressing TVAC in 3 days
• Submit a document change request with the above
  changes

17
Tower 4 and 5 - Conclusions

• Both towers well aligned and within stayclear
• The overall number of disconnected channels is
  very low
• All the silicon layers (but the bottom tray of
  tower 3) close to 100 efficiency
• Communication issue during TVAC solved
• Vacuum level still outspec during TVAC