1. Tracker Subsystem1 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

2. Tracker Subsystem2 GLAST LAT Project FM4/5 PSR, May 31, 2005 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)http://glast.pi.infn.it

3. Tracker Subsystem3 GLAST LAT Project FM4/5 PSR, May 31, 2005 Tower 4 - Assembly and components details Tower PN: LAT-DS-00722 (rev3) Tower SN: 4

4. Tracker Subsystem4 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

5. Tracker Subsystem5 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

6. Tracker Subsystem6 GLAST LAT Project FM4/5 PSR, May 31, 2005 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 the NCR can be closed and converted into a SLAC one for reference –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. Tracker Subsystem7 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

8. Tracker Subsystem8 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 (pre- ship) at the tower level is 99.7% (required 98%)

9. Tracker Subsystem9 GLAST LAT Project FM4/5 PSR, May 31, 2005 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)http://glast.pi.infn.it

10. Tracker Subsystem10 GLAST LAT Project FM4/5 PSR, May 31, 2005 Tower 5 - Assembly and components details Tower PN: LAT-DS-00722 (rev3) Tower SN: 5

11. Tracker Subsystem11 GLAST LAT Project FM4/5 PSR, May 31, 2005 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 the NCR can be closed –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. Tracker Subsystem12 GLAST LAT Project FM4/5 PSR, May 31, 2005 ~ 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!

13. Tracker Subsystem13 GLAST LAT Project FM4/5 PSR, May 31, 2005 Tower 5 - Efficiency worst layer is 99.4% overall efficiency (pre-ship) is 99.7%

14. Tracker Subsystem14 GLAST LAT Project FM4/5 PSR, May 31, 2005 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 the NCR can be closed –TVAC test of towers 4 and 5 was run with 2 systems in parallel, the NCR can be closed

15. Tracker Subsystem15 GLAST LAT Project FM4/5 PSR, May 31, 2005 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. Tracker Subsystem16 GLAST LAT Project FM4/5 PSR, May 31, 2005 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. Tracker Subsystem17 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