glast lat projectsept 3, 2003 anticoincidnce detector 1 glast large area telescope: planning meeting...

GLAST LAT Project Sept 3, 2003

AntiCoincidnce Detector 1

GLAST Large Area Telescope:GLAST Large Area Telescope:Planning MeetingSeptember 3, 2003AntiCoincidence Detector (ACD) Subsystem WBS: 4.1.6

David J. ThompsonThomas E. JohnsonNASA Goddard Space Flight CenterSubsystem Manager/Instrument Manager

[email protected]@nasa.gov

Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope



CRITICAL MILESTONE CHART

CriticalMilestone Jul

‘03Aug‘03

Sep‘03

Oct‘03

Nov‘03

Dec‘03

Jan‘04

Feb‘04

Mar

‘04Apr‘04

May

‘04Jun‘04

Jul‘04

Aug‘04

Sep‘04

Oct‘04

Nov ‘04

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 Pre-Environmental Review

13. ACD Vibration Test

14. ACD TVAC Test

15. ACD Pre-Ship Review

16. ACD Ship

17. ACD Ready for Integration

1

1



2003 20041 2 3 4 1 2 3 4

7/31/03

GLAST LAT ACD Summary Schedule

Task

Lat Instrument

ACD Milestones

Tile Shell Assembly

Tile Detector Assembly

Shell Assembly

Base Electronic Assembly

Base Frame Assembly

High Voltage Bias Supply

Analog ASIC

Digital ASIC

Front End Elec. Cards

Photo Multiplier Tubes

Micrometeroid Sh./Th. Blkt

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

CDR (S) I&TCDR

EM2 CAL PER PSR Flt

Flt

Spares

Flt

TU

FltDU EU

Flt

Flt (GAFE)

Flt (GARC)DU EU

Flt

Flt (240)CAL

Flt

ACD to LAT Integration (ND Date)

(Rec V-2)

Env. Testing

(Rec V-6)

10/15/04

ACD Ready for Integration 10/15/04

10/25/04

Test

Test



Near Term Milestones - 3 Month PlanNear Term Milestones - 3 Month PlanMilestone Description Date Status/Notes

First System Test w/ one FREE Board, HVBS, PMTs and TDAs

8/15/2003Completed

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 10/13/2003Vibration 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 11/20/2003Connectors complete; work started on

assembly

System Test w/ two FREE Boards, HVBS, PMTs and TDAs

11/28/2003Preliminary test Sept

Complete Fab of Flight TDAs 12/31/2003Completion December 03 by Fermi. Delay due

to manpower issue @ Fermi.

Complete PMT Assembly 1/30/2004PMT Housings and Bonding to complete 9/5.

PMT assembly area is ready. PMT Assembly to start 9/8.



InterdependenciesInterdependencies

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



Flight Hardware ProcurementsFlight 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 November4. Electronic parts – Completed, problem with HV capacitor5. HVBS Assy – August Start – February Completion. Problem

with HV capacitor causes minor (~ 1 week) delay.6. Shell Panels – Late September completion7. 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



Manufacturing PlansManufacturing Plans

1. TDA’s – Completed

2. ASICs qual, screen and test plan – In review

3. FREE and HVBS using standard process

4. PMT Assy Plan– In sign off

5. Mechanical Parts– Using standard plans

6. Clear Fiber Cables – Procedure in final review, beginning fab of EU units as well as training techs.



Unresolved AssumptionsUnresolved Assumptions

1. Thermal Blanket interface (outline drawing)

2. Grounding (outline drawing and grounding plan)

3. Rates data (resolved in principle)

4. Link up date for Grid to Base Frame interface

5. EGSE cable lengths – GASU to EGSE ~14m

6. GASU has to work in TVac and Vibration (with isolation)



New Issue #1New Issue #1

• TDA design problem

Interference between WFS and TDA tiedownat 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.



New Issue #2New Issue #2

• High Voltage Capacitor does not meet requirements. Dielectric strength out of spec.– 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

• Long lead part (original quote of 12 weeks)– 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.– 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.



Issues and Concerns - Issues and Concerns - updatesupdates

• 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.

• 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.



Issues and Concerns - Issues and Concerns - newnew

• 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



Issues and Concerns - Issues and Concerns - updatedupdated

• 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.



Open Design Issues - Open Design Issues - updateupdate

• 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.



Mechanical and EEE Parts - Mechanical and EEE Parts - updateupdate

• 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.• 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

– HVBS - 38 different parts types; 108 total parts per board• 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• One connector is not yet approved, waiting for screening

glast lat projectsept 3, 2003 anticoincidnce detector 1 glast large area telescope: planning meeting...

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