GLAST LAT Project
FM4/5 PSR, May 31, 2005
GLAST LAT Tracker
Tower-4/5 Pre-Ship Review
Luca.latronico@pi.infn.it
INFN-Pisa
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 4 - Assembly and test highlights
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Apr. 13-14, 2005 (INFN-Pisa) :
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Apr. 18-21, 2005 (INFN-Pisa) :
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Through customs in Roma airport
Full EIDP details at:
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Tracker Subsystem
TVAC test with tower 5
May 30, 2005 (Roma)
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VIB test
May. 23-27, 2005 (Alenia-Roma) :
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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) :
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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)
http://glast.pi.infn.it (soon available)
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 4 - Assembly and components details
Tower PN: LAT-DS-00722 (rev3)
Tower SN: 4
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
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
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
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
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 4 – Open NCRs
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INFN/PI-494: Bad channels out of spec
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INFN/PI-496: Vacuum level out of specification.
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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.
Common to Tower 5, see following slides.
INFN/PI-503: CPT reduction after TVAC
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Common to Tower 5, see following slides
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
~ 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 (>20 bad chans) already at SLAC and their
use was authorized by an MRB for schedule reasons
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 4 - Efficiency
• 3 layers with efficiency
< 99% as a consequence
of missing channels (see
previous slide)
• overall efficiency (preship) at the tower level is
99.7% (required 98%)
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 5 - Assembly and test highlights
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May 5-9, 2005 (INFN-Pisa) :
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May. 23-27, 2005 (Alenia-Roma) :
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Through customs in Roma airport
Full EIDP details at:
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Tracker Subsystem
TVAC test with tower 4
VIB test
May 30, 2005 (Roma) :
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assembly (tray stack, cables,
sidewalls, alignment, turn-over)
test (CPT)
http://glast.pi.infn.it (soon available)
9
GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 5 - Assembly and components details
Tower PN: LAT-DS-00722 (rev3)
Tower SN: 5
Tracker Subsystem
10
GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 5 – Open NCRs
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INFN/PI-492: Bad channels out of spec
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18 bad channels found in Pisa on X2 (9 dead, 9 disconnected)
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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.
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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
Common to Tower 4, see following slides.
INFN/PI-504: CPT reduction after TVAC
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Common to Tower 5, see following slides
Tracker Subsystem
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~ 45 disconnected channels overall (~0.08%).
All layers within specs, i.e. nb of bad chans <16, and stable
• new MCM encapsulant deposition, new MCM-PA gluing fixture, new shipping box are working!
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16
14
12
10
8
Number of Disconnected channels
20
18
6
4
2
0
Lev
X2
X4
Y5
Y7
X9
X10
Y13
X15
X16
X17
FM4/5 PSR, May 31, 2005
GLAST LAT Project
TKR Tower 5 Disconnected channels vs time
GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 5 - Efficiency
• worst layer is 99.4%
• overall efficiency
(pre-ship) is 99.7%
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
EGSE/TVAC – Communication problems with 2 towers
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Relevant NCR:
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Problem:
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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):
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INFN/PI-474
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
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TVAC test of towers 4 and 5 was run with 2 systems in parallel, the
Tracker Subsystem
NCR can be closed
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
Tower 4 and 5 – Vacuum level out of spec
Relevant NCR:
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70
Description:
Observations (see annex for
details):
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20
1.00E-03
10
0
-10
1.00E-04
-20
Tracker Subsystem
-30
-40
1.00E-05
-50
-60
1.00E-06
26/05/2005 12.00.00
26/05/2005 00.00.00
25/05/2005 12.00.00
25/05/2005 00.00.00
24/05/2005 12.00.00
24/05/2005 00.00.00
23/05/2005 12.00.00
23/05/2005 00.00.00
22/05/2005 12.00.00
-70
22/05/2005 00.00.00
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.
21/05/2005 12.00.00
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1.00E-02
30
21/05/2005 00.00.00
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40
20/05/2005 12.00.00
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Date
101 Cold Plate
105 Cold Plate -Y
10 TWR5 center bot
35 TWR4 swall -X n.1
102 Cold Plate +X
01 TWR5 center top
12 TWR5 bot C-O +X
40 TWR4 swall +X n.9
103 Cold Plate +Y
02 TWR5 top C-O -X
32 TWR4 center top Tray
43 TWR4 bot c-o +X
104 Cold Plate -X
04 TWR5 swall -X n.1
33 TWR4 top c-o -X
Pressure
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Pressure (Torr) 1
The vacuum level was mostly
outspec during the test (specs
call for 5E-5 torr)
1.00E-01
60
20/05/2005 00.00.00
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INFN/PI-458, INFN/PI-459
80
1
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1.00E+00
90
Temperature (°C)
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
CPT reduction for TVAC
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Reference NCR
– 503 and 504
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Description
– TE101 (leakage current and power consumption test) not performed after towers 4
and 5 TVAC test
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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
Tracker Subsystem
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GLAST LAT Project
FM4/5 PSR, May 31, 2005
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
Tracker Subsystem
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