GLAST Large Area Telescope: Calorimeter (WBS 4.1.5)

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GLAST Large Area TelescopeCalorimeter (WBS
4.1.5)

• W. Neil Johnson
• Naval Research Lab
• Calorimeter Subsystem Manager
• johnson_at_gamma.nrl.navy.mil

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Calorimeter Subsystem

• Outline
• Programmatic Status
• Lehman Review Recommendation Status
• Technical Progress
• Assembly Test
• Resources
• Issues / Concerns

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Programmatic Status

• In France the CNES Scientific Program committee
  issued positive recommendation and re-confirmed
  the French participation in GLAST.
• A CNES Preliminary Requirements Review will occur
  in October to authorize the technical approach
  and French organization. This review will secure
  the budget for the implementation phase.
• Management activities have focused on creating
  CAL WBS, revised plans, schedules, and costs for
  the development and fabrication of the
  calorimeter
• Interim Design Review held in Paris, June 11
  13, focused on detailed review of the Swedish and
  French responsibilities, interfaces, work flow
  and schedules.
• Financial problems in France for this FY have
  been resolved and, as a result, the PIN
  photodiode procurement (US) for EM diodes was
  released.
• Significant efforts have been placed in improving
  or creating CAL documentation for PDR required
  specifications, plans and procedures have been
  identified and responsible persons have been
  assigned.
• Completed CAL Subsystem Peer Design Review on
  July 27.

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Lehman Review Recommendation Status

• Sign and implement international agreements
• Drafts exist of MoA among participating
  laboratories and of NASA-CNES International LoA.
• MoA has been updated by US and French
  participants no apparent action on LoA.
  Successful PRR should permit French signatures.
• Organize French efforts and commitment to roles
  and responsibilities
• Done. Documented in MoA and WBS.
• Develop bottoms up resource-loaded schedule
• Done. Delivered to PMCS on 7/20/01. Revisions
  continue.
• Update the cost estimate and assign adequate
  contingency
• Bottoms up costing completed. Contingency
  analysis on-going. Overall funding and profile
  are problems.
• Resolve PIN diode glue problems
• Resources have been applied. Test and selection
  program identified. Backup solution identified.
  Tests are continuing.
• Define responsibilities for procurement,
  qualification and testing of ASICs
• Done. SLAC designs and tests prototypes. NRL
  does the rest.

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Technical Progress

• CsI Crystals
• The first two crystal optical test benches have
  been completed at NRL and have been shipped to
  Sweden.
• First metrology test bench has been completed in
  Sweden.
• First 24 crystals from Amcrys-H have been
  received and tested in Sweden.
• The crystals were generally as expected although
  several crystals were slightly out of
  specification. These out of spec conditions were
  generally either over sized or incorrect light
  tapering along the crystal.
• PIN Photodiode
• 1st photodiode delivery expected Aug 15th.
• Flex cable design for connection of PIN to
  readout electronics has been iterated with
  mechanical and electrical engineering.

13 CsI Crystals from Amcrys-H
BTEM PIN diode and flex cable
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Technical Progress (2)

• Crystal Detector Elements (CDE)
• New baseline for CDE includes optical wrapping
  (VM2000) attached to CsI crystal rather than
  applied to structure walls.
• Mylar tape on corner bevels holds 4 VM2000
  strips.

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Technical Progress (3)

• PIN Photodiode CsI Crystal Bonding
• Studies of potential bonding material continue at
  IN2P3 and NRL.
• IN2P3 contract with CETIM to model the bonding
  problem
• Rejects hard epoxies
• Soft epoxy and silicone are OK.
• Bonding Plan
• Test soft epoxy silicone elastomer with primer
• A vacuum gap is the backup solution.
• Thermal (-30C to 50C) cycling in vacuum
  environment tests between glass and CsI with
  surface preparation.
• The type of bonding for the EM will be chosen
  after 12 thermal-vac cycles. A set of
  photodiodes that are larger than CAL diode will
  be bonded on CsI and ultimately tested for 100
  cycles.
• Aging tests ( thermal cycling and irradiation)
  are performed on these glues with particular
  attention to transparencies
• Bonding for FM will be reviewed after completion
  of test program and experience with EM
  fabrication.

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Technical Progress (4)

• Pre Electronics Module (PEM)
• Verification Model 2 (VM2) tooling has been
  designed and is being fabricated
• Baseplate design has been modified to meet LAT
  Grid stiffness requirements.
• Preliminary thermal and structural analysis have
  been completed.
• VM2 will contain 12 CDE and 84 mass dummies
• Science performance evaluation before LAT PDR

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Technical Progress (5)

• First prototype GCFE1 ASIC received at SLAC in
  June 01
• Contains all functionality
• Analog Multi-gain amplification, shaping,
  auto-range gain selection, trigger
  discriminators, five 7-bit DACs
• Digital VHDL synthesized and auto placerouted
  digital circuits (10,000 gates) for
  configuration/mode registers, writeread
  state-machine, data-acquisition state-machine
  logic, etc.
• Digital circuits are fully functional, tested up
  to limit of test-box, 40 MHz, (f20 MHz is
  nominal)
• Found capacitor-to-capacitor short of
  calibration-circuit to gain-selection circuit.
  Bug discovered in linear capacitor extract
  software
• Analog amplifier and shaper are functional after
  cut of trace on chip
• Single range calibration, charge-amplifier with
  external gain select, shaping, post-amplification,
  auto-ranging, acquisition sequence,
  rail-amplifiers, trigger discriminators are fully
  operational. Performance tests are in progress.
• 2nd Version GCFE2 received last week, has
  Single-Event Upset hardened registers
  incorporated
• 3rd version GCFE3 with short fixed to be
  submitted July 28.

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Assembly Test in Europe

• CsI crystals delivered to Sweden at rate of 200
  per month.
• Starts early. Last crystals delivered 5 months
  before needed.
• PIN photodiodes delivered to France at rate of
  600 per 5 weeks.
• Delivery rate not a problem for Hamamatsu.
• CDE Assembly and Test at rate of 200 per month
  ( 6 days per crystal)
• PEM Assembly in France requires 7 weeks per
  module
• Assembly, Metrology
• Cosmic muons
• Environmental Thermal vac vibration (TBR)
• Final test (cosmic muons)

Total Processing Time 9 weeks per module
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Module Assembly and Test Schedule

• Duration of assembly and test phases (working
  days for each Module)

Phase Module Module Module Module
EM QM, 1-2 3-6 7-16
PEM Acceptance 14 9 8 5
Elect Integration 25 14 10 9
Calibration 12 6 5 4
Environmental 28 17 11 11
Pre-ship Verification 10 7 6 6
Margin 5 5 8 8
Total per Module 94 58 48 43

• The challenge sustained receipt, assembly, test
  and delivery of a module every two weeks.
• One PEM arrives at NRL every two weeks.
• Five Modules in process at once.
• One Module ships to LAT Integration Site (SLAC)
  every two weeks.
• (but last Module arrives at SLAC five weeks
  before required date.)

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Assembly and Test Schedule
Module Planned Module Delivery Date LAT Schedule Integration Date Weeks delivery is early
Qual Model (FM A) 13 May 03 15 Aug 03 13
Flight Spare (FM B) 03 Jun 03 15 Aug 03 10
Flight Model 1 29 Jul 03 03 Nov 03 14
Flight Model 2 19 Aug 03 03 Nov 03 11
Flight Model 3 27 Aug 03 02 Jan 04 18
Flight Model 4 10 Sep 03 02 Jan 04 16
Flight Model 5 24 Sep 03 15 Jan 04 17
Flight Model 6 08 Oct 03 15 Jan 04 14
Flight Model 7 15 Oct 03 29 Jan 04 15
Flight Model 8 29 Oct 03 29 Jan 04 13
Flight Model 9 12 Nov 03 12 Feb 04 13
Flight Model 10 26 Nov 03 12 Feb 04 11
Flight Model 11 10 Dec 03 26 Feb 04 11
Flight Model 12 24 Dec 03 26 Feb 04 9
Flight Model 13 07 Jan 04 10 Mar 04 9
Flight Model 14 21 Jan 04 10 Mar 04 7
Flight Model 15 04 Feb 04 24 Mar 04 7
Flight Model 16 18 Feb 04 24 Mar 04 5

• Delivery for integration into LAT
• Instrument integration schedule specifies
  required Ready For Integration (RFI) dates.
• RFI rate Two Modules every two weeks.
• Too much work in parallel, so well start earlier
  and stretch deliveries.
• Typical delivery rate One Module every two
  weeks.
• Plan FMs arrive at LAT Integration Site 5 to 18
  weeks earlier than required.
• Some margin for slippage.

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Resources - Mass Estimate
Mass Reserve Analysis 90 of reserve held at LAT
level
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Resources - Power Estimate
Conditioned Power at 3.3 70 V For each AFEE
board (4 / Module)
Power Reserve Analysis 75 of reserve held at
LAT level
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Resources - Cost Estimate
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Cost Comparison w/ Proposal
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Issues / Concerns

• CAL project is working hard to make up for lost
  time. Additional personnel are being added in US
  and France to support engineering development.
• Near term schedule to CDR will be a challenge.
  Critical near term milestones include
• Determination of the PIN diode bonding solution
  and verifying its ability to meet the performance
  and environmental requirements.
• Completion of VM2 prototype, demonstrating
  science performance (before PDR) as well as
  mechanical design verification (post PDR).
• Completion of GCFE analog ASIC performance
  testing and obtaining completely functional parts
  for EM fabrication.
• Completion of EM fabrication and test program
  prior to CDR.
• Revised CAL cost and schedule have just recently
  (7/20) been submitted to SLAC.
• CAL funding is insufficient and profile is not
  optimal. Resources lost in FY 02 reappear too
  late (FY 04) to be of much use.
• More iterations are required
• Environmental test plan needs more consideration.
• Cost issues
• Over-testing issues

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Backup Material
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Test Matrix
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Thermal Simulation of Bonding to CsI

• Thermal (-30,20) simulation of constraints on
  different glues curing at 20C by CETIM

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Development Program

• PEM VM2 Prototype
• Mechanical Model w/ 12 CDE and 84 dummy crystals
• CDE Performance testing before LAT PDR
• Environmental testing completed by Dec 01
• Front End Electronics
• GCFE Test Board Radiation Testing - Nov 01
• VM Board, GCFE GCRC FPGA
• Functional testing with CDE
• Radiation testing Jan 02
• Engineering Model (EM)
• Form and function of flight units, commercial
  grade parts where required, fully populated PEM
• Functional testing
• Environmental testing
• Beam tests
• Delivered to SLAC for TDF, software development

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VM2 EM Development
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Current Estimate vs Funding