Transcript GLAST Proposal Review

GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
Sept 3, 2003
GLAST Large Area Telescope:
Planning Meeting
September 3, 2003
AntiCoincidence Detector (ACD)
Subsystem
WBS: 4.1.6
David J. Thompson
Thomas E. Johnson
NASA Goddard Space Flight Center
Subsystem Manager/Instrument Manager
[email protected]
[email protected]
AntiCoincidnce Detector
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GLAST LAT Project
Sept 3, 2003
CRITICAL MILESTONE CHART
1
Critical
Milestone
1.
Shell Subassembly
2.
Analog ASIC
3.
Digital ASIC
4.
Base Frame
Assembly
5.
HVBS Flight Unit
6.
PMT Flight Unit
7.
Tile Detector
Assemblies
8.
Clear Fiber Cables
9.
Mechanical
Subsystem
(ready for I&T)
10.
Free Flt Unit
Functional Test
11.
ACD Functional
Test
12.
ACD PreEnvironmental
Review
13.
ACD Vibration Test
14.
ACD TVAC Test
15.
ACD Pre-Ship
Review
16.
ACD Ship
17.
ACD Ready for
Integration
Jul
‘03
AntiCoincidnce Detector
Aug
‘03
Sep
‘03
Oct
‘03
Nov
‘03
Dec
‘03
Jan
‘04
Feb
‘04
Ma
r
‘04
Apr
‘04
Ma
y
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Jun
‘04
Jul
‘04
Aug
‘04
1
2
Sep
‘04
Oct
‘04
Nov
‘04
GLAST LAT Project
Sept 3, 2003
GLAST LAT ACD Summary Schedule
7/31/03
2003
Task
1
Lat Instrument
ACD Milestones
2004
2
3
4
1
2
3
CDR
4
(S) I&T
CDR
EM2
CAL
PER
PSR
Flt
10/15/04
Tile Shell Assembly
Flt
Tile Detector Assembly
Spares
Shell Assembly
Flt
Base Electronic Assembly
TU
Base Frame Assembly
Flt
DU
EU
High Voltage Bias Supply
Flt
(Rec V-6)
Analog ASIC
Flt (GAFE)
Test
(Rec V-2)
Digital ASIC
Test
DU
Flt (GARC)
EU
Front End Elec. Cards
Photo Multiplier Tubes
Micrometeroid Sh./Th. Blkt
Flt
Flt (240)
CAL
Flt
Mech Subsys (ready for I&T)
ACD I&T
TSA Integration
BEA Integration
ACD Integration/Env. Test
ACD Prep, Ship, RFI
ACD to LAT Integration
AntiCoincidnce Detector
Env. Testing
ACD Ready for Integration
ACD to LAT Integration (ND Date)
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10/15/04
10/25/04
GLAST LAT Project
Sept 3, 2003
Near Term Milestones - 3 Month Plan
Milestone Description
Date
Status/Notes
Completed
First System Test w/ one FREE Board,
HVBS, PMTs and TDAs
8/15/2003
Base Frame Channel Fabrication start
8/29/2003
Ready for fabrication
Complete Fab of TDA tiedowns
9/30/2003
Drawings, procedures in signoff
Receive/Test Flight ASICs (rapid-package)
9/30/2003
Test procedures and test equipment ready
Fab Flight HVBS PCBs
10/13/2003
Vibration Testing complete. Currently in TVAC
testing.
Complete Flight Mechanical Drawings
10/31/2003
Complete Design on MGSE and EGSE
10/31/2003
New designer just started
Complete Assembly of Flight Shell
10/31/2003
Receive Sep03; Strength test Oct03.
Start Testing on BEA EU
11/10/2003
We will test 3 HVBS eus during this test.
Complete Fab of Clear Fiber Cables
11/20/2003
Connectors complete; work started on
assembly
System Test w/ two FREE Boards, HVBS,
PMTs and TDAs
11/28/2003
Complete Fab of Flight TDAs
12/31/2003
Complete PMT Assembly
AntiCoincidnce Detector
1/30/2004
Preliminary test Sept
Completion December 03 by Fermi. Delay due
to manpower issue @ Fermi.
PMT Housings and Bonding to complete 9/5.
PMT assembly area is ready. PMT
Assembly to start 9/8.
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GLAST LAT Project
Sept 3, 2003
Interdependencies
1. Funding – IPO, availability of LAT resources, GLAST Project,
FY03 carryover
2. ASICs – LAT Electronics group support, Product Assurance
(packaging, qual, screen, and test). Status on rapid package as
well as flight packaging?
3. Delivery of FREE Boards and Parts to Electronics
4. EGSE/G3 – Ongoing development with I&T and electronic
groups
5. ACD/GASU – Cable details and system clock testing. Need
signed off and configuration controlled drawing for cables.
6. Grid to Base Frame installation – Outline drawing and available
date for installation
AntiCoincidnce Detector
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GLAST LAT Project
Sept 3, 2003
Flight Hardware Procurements
1. TDA’s – December completion, design problem could impact
delivery.
2. ASICs – Receive rapid packaged ASICs on ?, Submit ASICs for
flight packaging 1-2 weeks after receiving rapid packaged chips
3. FREE PWBs – September/October procure, available November
4. Electronic parts – Completed, problem with HV capacitor
5. HVBS Assy – August Start – February Completion. Problem
with HV capacitor causes minor (~ 1 week) delay.
6. Shell Panels – Late September completion
7. PMT parts – All parts procured, all housings completed next
week, RN PCB’s due in soon, HV Cap will delay assembly
completion.
8. Base Frame Mechanical Parts– July-August, complete
December
9. TSA Mechanical Parts – July-August, complete December
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GLAST LAT Project
Sept 3, 2003
Manufacturing Plans
1.
2.
3.
4.
5.
6.
TDA’s – Completed
ASICs qual, screen and test plan – In review
FREE and HVBS using standard process
PMT Assy Plan– In sign off
Mechanical Parts– Using standard plans
Clear Fiber Cables – Procedure in final review, beginning fab of
EU units as well as training techs.
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GLAST LAT Project
Sept 3, 2003
Unresolved Assumptions
1.
2.
3.
4.
5.
6.
Thermal Blanket interface (outline drawing)
Grounding (outline drawing and grounding plan)
Rates data (resolved in principle)
Link up date for Grid to Base Frame interface
EGSE cable lengths – GASU to EGSE ~14m
GASU has to work in TVac and Vibration (with isolation)
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GLAST LAT Project
Sept 3, 2003
New Issue #1
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TDA design problem
Interference between
WFS and TDA tiedown
at this point
Three Potential Solutions
identified.
– Move some TDA tiedowns
– Reduce bending radius of
WSF
– Decrease size of TDA
tiedown
Potential impact to shell panels and TDA Tiedowns
Good news is that Fermi staffing issue is under control, bad
news is they have to refocus their efforts to helping solve this
problem.
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GLAST LAT Project
Sept 3, 2003
New Issue #2
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High Voltage Capacitor does not meet requirements. Dielectric
strength out of spec.
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Long lead part (original quote of 12 weeks)
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Predicted life time of capacitor would be reduced by a factor of ~2.5
No life testing results available to verify predictions. Engineers expect
that actual would be worse than predicted
Ordered ~16 weeks ago. Parts came in a little late and screening on first
batch has just been completed
Manufacture has agreed to replace part at no cost. Negotiating for a
shorter lead time (~7 weeks may be possible) as well as keeping 40 of
the original parts so that testing program can continue.
Part is used in PMT assembly as well as HVBS’s.
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Used on 2nd (middle) resistor network board. This will delay PMT
assembly completion. Work-a-rounds include installing all 1st boards as
well a reshuffling work for assembly techs. Will assemble qual PMTs
using “non-spec” parts.
Impact to HVBS will be minimal. Proceed with qual unit HVBS using
“non-spec” part.
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GLAST LAT Project
Sept 3, 2003
Issues and Concerns - updates
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Need for a final Qualification and Screening Plan for ASICs is a concern
– LAT has a general Q&S Plan for ASICs
• Issue has been the specific implementation (particularly testing)
needed for the ACD ASICs
Working with LAT Parts Control Board in consultation with Goddard
parts engineers to finalize details of the plan. Agreed in principle, but
documentation is still needed. Test boards are being designed.
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Shortage of test equipment at Goddard is a concern
– In particular, equipment needed for the ASIC Q&S program seems
to be in short supply
Working with Goddard local laboratory and Engineering Directorate to
locate or repair needed equipment. Not much success so far.
Requested Goddard funding (~$60K) for additional equipment. None
provided yet, requiring unbudgeted expenditures to keep testing
program on schedule.
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GLAST LAT Project
Sept 3, 2003
Issues and Concerns - new
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Reduction of support for ACD TDA production at Fermilab is an issue.
– Accelerator shutdown, required vacation, and extended medical
leave have seriously reduced the staffing available to continue the
TDA fabrication.
Issue appears to be resolved. Axiom operator (actually 2 this week)
vacancy has been resolved. They will work a second shift if required to
maintain schedule. Have been assured that this job is a high priority,
second only to the beam shutdown. Alex and I will be going to Fermi
next week.
Reduction of support for ACD mechanical engineering at GSFC is an
issue.
– Problem in another flight project (XRS on Astro E2) has siphoned off
some of the time of ACD mechanical engineers
Working with Goddard management to retain enough support to
maintain schedule. Receiving additional support to backfill support lost
to XRS
ASIC Yield – 50% yield at ambient temperature prior to thermal cycling
or burn-in
AntiCoincidnce Detector
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GLAST LAT Project
Sept 3, 2003
Issues and Concerns - updated
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Late delivery of G3 Test Stand/EGSE from LAT Electronics and I&T is a
concern
– Scheduled for August, recently slipped to November/December
• Planned for testing of multiple FREE cards and Electronic
Chassis, scheduled for August - November
– Developing workarounds, using older G2 Test Stands and bench
electronics. Interfaces are less like the flight interface, but should
allow much of the testing.
– Developing the G3 software before the arrival of the hardware, to
minimize the startup delay once the G3 Test Stands arrive.
– G2 will be testing flight hardware, need documentation.
ACD cost increases and availability of FY03 funding is an issue
– Cost to Complete exercise identified increased costs for ACD
– Goddard Engineering Directorate has provided additional Civil
Service support, replacing contractors with CS personnel wherever
a qualified Civil Servant could be found.
– GLAST Project has offered some support.
– Additional ACD funding included in the current LAT request.
AntiCoincidnce Detector
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GLAST LAT Project
Sept 3, 2003
Open Design Issues - update
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OPEN: Outline drawing that defines some interfaces with LAT is still
not complete (blanket attachment, grounding, cable tie-downs, optical
survey mounts). Action Plan: Work with LAT mechanical design team
to resolve open issues by August 29. Status unchanged.
CLOSED: LAT Electronics group requested a change in the backshell
of the connector to the ACD. This change requires a change in the
bracket that holds the connector, and this bracket is a structural
element. Modification should be straightforward, but must be
analyzed. Action: Decided to stick with original design.
CLOSED: FREE Board design updates and finalization. Action: Design
complete and in fabrication.
OPEN: Need updated interface loads following Grid design changes.
Action Plan: Review ACD analysis when updated loads are received.
ACD will not delay fabrication of mechanical components due to this
open issue (slight risk in doing so). Status unchanged.
OPEN: Discovered interference between some wave shifting fibers
and TDA flexures. Action Plan: Re-design and re-analyze to resolve.
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GLAST LAT Project
Sept 3, 2003
Mechanical and EEE Parts - update
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Mechanical Parts and Materials - ALL APPROVED
PMTs – Qualified, tested, and screened (final report in draft form now)
EEE Parts
– FREE - 36 different part types; approximately 830 parts per board.
All parts approved by PCB with the following exceptions.
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HVBS - 38 different parts types; 108 total parts per board
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MAX145 and MAX5121 being qualified by GSFC parts group (chips
provided by Calorimeter).
ASICs in fabrication. S&Q plan is complete and has been reviewed by
members of the PCB. Detailed GARC test procedure in review and
draft GAFE test procedure is being circulated
MAX494 was recently approved following radiation testing
4 parts are not yet approved (DPA needed on 3 capacitors, screening
needed for one wire)
High voltage capacitor was rejected, did not meet specification
Resistor network - 9 different parts types; 26 total parts
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One connector is not yet approved, waiting for screening
AntiCoincidnce Detector
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