Status of GLAST Large Area Telescope - slac. · PDF fileStatus of GLAST Large Area Telescope...

SLAC EPAC, SLAC, November 20, 2002

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GLAST Large Area Telescope ProjectGLAST Large Area Telescope Project-- Presentation at EPAC Nov 21, 2002 Presentation at EPAC Nov 21, 2002 --

Status of GLAST Large Area Telescope

Nov. 21, 2002Tuneyoshi Kamae

for the LAT Collaboration

Plan of TalkOverall schedule

Anti Coincidence DetectorTracker Tower

CalorimeterIntegration and Testing

Strengthening Plan


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LAT Progress reportLAT Progress report-- LAT Overview LAT Overview --

Overview of Large Area Telescope


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LAT Progress reportLAT Progress report-- Overall Schedule Overall Schedule --

Overall Schedule: Very tight schedule ahead of usJanuary 8-11, 02 Preliminary Design Review (NASA) and Baseline Review (DOE)April 16-18, 02 SLAC Internal ReviewJuly 30-Aug 1, 02 Delta PDR (NASA) and Baseline Review (DOE)August 23, 02 Selection of Spectrum Astro Inc. as the Spacecraft builder announced October 22-25, 02 Collaboration MeetingNovember 12-13, 02 Quarterly Review Fall 02 (DOE/NASA)NOWDecember 02 Subsystem Engineering Model delivery startsFebruary 03 Silicon Tracker EM deliveryMarch 03 Integration of EM Tower startsApril 03 Calorimeter EM deliveryApril 03 Test on EM Tower with cosmic ray and nuclear gammas (17.6MeV) startsJune 03 Test on EM Tower completeApril 03 Critical Design Review (DOE) and CD3 (DOE)April 03 Flight Model production beginsOne Year from NOWJanuary 04 Qualifying Towers arrives to SLACMarch 04 Four Towers assembled for the SLAC Beam TestApril-July 04 SLAC Beam Test


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LAT Progress reportLAT Progress report-- Anti Coincidence Detector (1/4) Anti Coincidence Detector (1/4) --

Base Electronics Assembly (BEA)

Tile Shell Assembly (TSA)

Prototype ACD tile read out with Wavelength Shifting Fiber

TILE SHELL ASSEMBLY89 Plastic scintillator tilesWaveshifting fiber light collection (with clear fiber light guides for long runs)Two sets of fibers for each tileTiles overlap in one dimension8 scintillating fiber ribbons cover gaps in other dimension (not shown)Supported on self-standing composite shellCovered by thermal blanket + micrometeoroid shield (not shown)

BASE ELECTRONICS ASSEMBLY194 photomultiplier tube sensors (2/tile)12 electronics boards (two sets of 6), each handling up to 18 phototubes. Two high voltage power supplies on each board.

ACD Overview


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Qualification phototube in housing with resistor network.

ACD Design Status

Designs Complete or Nearly Complete•Shell•Flexures•Tiles•Fibers•Optical connectors•Phototubes in housings•Digital ASIC•FREE card•High Voltage Bias Supply•Base frame•Micrometeoroid shield/thermal blanket

Designs in Progress•MGSE•Analog ASIC

Open Trade Studies•Optimization of performance (gaps and light collection)


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Position from the edge of a tile [cm]

Rel

ativ

e pu

lse

heig

ht

Along WLS fiber #8Along WLS fiber #7

Along WLS fiber #6Along WLS fiber #5Along WLS fiber #4

Along WLS fiber #3Along WLS fiber #1

Preliminary

Preliminary

Red: Readout from PMT #1Black: Readout from PMT #2

Pulse height uniformity over a scintillation tileACD Test Results


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ACD Two Top IssuesAnalog ASIC (GAFE) – Some problems in the analog ASIC design.

Modified the design for latest fab run. Latest GLAST ACD Front End ASIC version due back in Dec. SLAC LAT team expertise and GSFC expertise are working together to help solve the other problems.

Tile Gap/Efficiency Issues – The gaps between tiles reduce the ACD efficiency.

Requirements for GLAST ACD Front End ASIC


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LAT Progress reportLAT Progress report-- Silicon Tracker (1/6) Silicon Tracker (1/6) --

Overview of Silicon Tracker (1/2)

19 stiff composite “tray” panels support SSDs on both faces with electronics on two sides.

Converters are on the bottom face, just above the SSD plane2-mm gap between trays

16 layers of tungsten converter foils.12 layers of 3% X0 convertersFollowed by four 18% layers

18 x and 18 y SSD planes.Carbon-fiber sidewalls conduct heat to the base and stiffen the module.Electronics are based on 2 ASICs, PC boards, and custom flex cables.31.6 kg mass per module.10.5 W of power per module.

Readout Cable

Multi-Chip Electronics Module (MCM)

2 mm gapCarbon-Fiber Wall

19 Carbon-Fiber Tray Panels


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Overview of Silicon Tracker (2/2)

Cable PlantUCSC

SSD Procurement, TestingJapan, Italy, SLAC

Electronics Design, Fabrication & TestUCSC, SLAC

Tracker Module Assembly and Test Italy

Tray Assembly and TestItaly

SSD Ladder AssemblyItaly

Composite Panel & ConvertersEngineering: SLAC, Hytec, and ItalyProcurement: Italy

2592

10,368

342

648

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Module Structure (walls, flexures, thermal-gasket, fasteners)Engineering: SLAC, HytecProcurement: SLAC

342


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Silicon Tracker Design Status (1/2)

ASIC design and test:GLAST Tower Front-end Electronics design is fully functional.GLAST Tower Readout Controller is working but needs some logic corrections for flight (new logic under test in FPGAs).3 complete Multi-Chip Modules (26 chips each) are under test.Mini-MCM connected to full SSD ladder demonstrated satisfactory noise performance.

(see next slide)Radiation testing in progress.

EM Multi-Chip Module production:In progress at Teledyne Electronics Technologies

SSD procurement total: > 4600 delivered.> 3500 tested by LAT.

Ladder assembly:EM ladders completed.Flight ladder assembly begun at G&A Engineering (30 in test).

Tray fabrication:At least 16 EM panels fabricated at Plyform.Fixtures are ready for Kapton, tungsten, and SSD mounting.

Electronics:GTRC/GTFE ASIC designs need some small modifications to increase timing margin in data transfer between the two.

Bottom Tray and Tower-Grid Interface:Invar closeout has been investigated and is now only a backup solution.Reinforcement of the existing design is being followed in work with COI and Hytec. Coupon testing and preparation of a prototype tray will be completed one month from now.Hytec will be updating the tower model, completing analysis work, and preparing load and vibration tests.


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Silicon Tracker Test Results: Ladder production began

Figure: Distribution of sigmas from the fits, interpreted as equivalent noise in electrons at the amplifier input.

0 400 800 1200 1600 2000 2400 2800Noise

0

20

40

60

0

20

40

60

0

20

40

60

G

F

F_NO_DET

Mean = 691

Mean = 1897

Mean = 1647

Noise Distributions


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Silicon Tracker Test Results: Ladder production began

0 100 200 300Channel Number

0

2

4

6

Noi

se H

itsFigure. Noise occupancy per channel. Plotted for each channel is the number of noise hits in 1.5 million random triggers. > a few scattered noise in the entire LAT (total 10**6 channels)


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Silicon Tracker Two IssuesSilicon Tracker Two Issues

Bottom tray and Grid interface design• Two design paths are under investigation:

Reinforcement to the original Carbon-Carbon designInvar based design

• Data needed to make decision are due in mid December

ASIC Design and Production• Some modifications are needed in some ASICs

Logic errors remain in the latest GTRC prototype ICNeed a little more margin for data transfer btwn GTFE and GTRC (20MHz at 2.5V)Some production of GTFE-G are unstable at low threshold

• Corrections are made and new submissions will solve the problems. An option for the 2nd problem above may require a higher voltage (eg. 2.8V)


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LAT Progress reportLAT Progress report-- Calorimeter (1/4) Calorimeter (1/4) --

CsI Detectors + PIN diodes (both ends)

Readout ElectronicsCarbon Cell Array

Al Cell Closeout

Al EMI Shield Mounting Baseplate

Modular Design

4 x 4 array of calorimeter modules

Each Module8 layers of 12 CsI(Tl) Crystals

Crystal dimensions: 27 x 20 x 326 mmHodoscopic stacking - alternating orthogonal layers

Dual PIN photodiode on each end of crystals.

Mechanical packaging – Carbon Composite cell structure

Electronics boards attached to each side.Electronic readout to connectors at base of

calorimeter.Outer wall is EMI shield and provides

structural stiffness as well.

Calorimeter Overview (1/2)


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CDE AssemblyFrance (CEA/DAPNIA)

PIN Diode(each end)

CsI Crystal

Optical Wrap

TwistedPair Wires

Mechanical StructureFrance (IN2P3/Ecole Polytechnique)

Front-End ElectronicsNRL, SLAC

PEM AssemblyNRL

Module Assemblyand Test, NRL+collab

CsI Crystals: Sweden (KTH)

16 flight modules + 2 spares

1728

18

18

72

18

Calorimeter Overview (1/2)


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Swales CDE BondDesign Status of Crystal Detector ElementCrystal detector elements (CDE) for the EM have been completed

at Swales.107 CDE have been completed (96 or 80 required).3 CDEs have been fabricated from DPDs with silicone

optical windowLight yield testing on 1st CDEs show

> 8000 e-/MeV (reqmt >5000).

Design Status of Mechanical StructureEM Structure delivered to NRL by LLR/Ecole

Polytechnique in AugustCloseout plate finalized (AFEE redesign issue)Elastomeric bumpers and other plastic parts are in fab.CDE insertion MGSE delivered to NRL.CDE integration test w/ structure occurred in October.

Assembly procedure developed and tested w/ support of LLR at NRL.Design Status of Analog Front End Electronics

ASICs GCRC V4, GCFE V7 have been packaged and tested.PreEM AFEE-X board fabricated and tested.EM AFEE-Y and AFEE-X board layout complete.

Procurements for fab and assembly are in process.


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Dual PIN Photodiode Flight QualificationAggressive program to validate and qualify alternate optical window encapsulantInitiate long-lead ceramic tooling and diode masks procurement while study of

encapsulant continuesThe silicone encapsulant need to be qualified.

Crystal Detector Elements from FranceAvailability of CDEs from France for the EM program is schedule risk.Mitigation: use all USA CDEs and test French CDEs in potential (discussed but not

approved) EM2.AFEE/CDE performance problem

ASIC and/or other electronics board problem discovered in EM testing would have significant cost and schedule impact. (No currently known problems)

EM is 1st integration of AFEE board with detectors in an operational system.Mitigation: continuing testing with prototype boards and CDE.

Calorimeter Three Top IssuesCalorimeter Three Top Issues


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I & T Responsibility

LAT Progress reportLAT Progress report-- Integration and Testing (1/3) Integration and Testing (1/3) --

Vibe Random vibrate/sine sweep Acc Acceptance test levelAc Acoustic QU Qualification UnitT-C Thermal-cycle at 1 atmosphere EM Engineering ModelT-V Thermal-vacuum cycle test TM Thermal modelEMI Electro-magnetic interference test CU Calibration Unit

FU Flight UnitCalibration unit I&T Cal CalibrationFlight unit/spares I&T FS Flight Spare

I&T: Beam test CU – 4 towers

Cal

Elec: EM2 Elect. Modules

TKR: QU FS from TKR fab

CAL: F1-2 from CAL fab

CAL: QU- FS from CAL fab

TKR: F1-2 from TKR fab

Calibration Unit - CU

Obs: Support Vibe/Ac

Acc

Obs: Support T-V

Acc

Obs: Support EMI

Acc

I&T: LAT Assembly, Test

Acc, Cal

Elec: Flt Elec. Mod. to LAT I&T

CAL: F3-16 from CAL fab

TKR: F3-16 from TKR fab

Mech: Flt Grid from Mech

ACD: ACD to LAT I&T

Flight LAT - FUI&T: LAT Functional, Thermal, Airborne cosmic E to E

Acc, Cal, T-C

TKR/CAL: F1,2 from CU

I&T: LAT Environmental Tests Acc, Cal, T-V

Integration and Calibration Flow

Elec: SIU

Mech: Flt Rad’s from Mech


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Brems beam, simultaneously all γ energy bins from <20 MeV to 28 GeV @ variety of angles and positions.

Tagged photons 20 to 1500 MeV, norm incidence.

Test + MC, Analysis.

100 MeV< 3.5° front, < 6° back

10-300 GeV< 0.15° front, < 0.3° back

Single Photon Angular Resolution – 68% (on-axis)

5.2.5

Brems beam, simultaneously all γ energy bins from <20 MeV to 28 GeV @ variety of angles and positions.


>8000 cm2Peak Effective Area5.2.3

Van de Graaff 17.6 MeV photons.Tagged photons 20 to 1500 MeV, norm

incidence.Positrons 1, 2, 5, 10, 28, 45 GeV, @

variety of angles and positions.


≤ 50 %20–100 MeV≤ 10 % 1-10 GeV≤ 20% 10-300 GeV

Photon Energy Resolution (normal incidence)

5.2.2

Van de Graaff 17.6 MeV photons.Tagged photons 20 to 1500 MeV, norm

incidence.Brem beam, simultaneously all γ energy

bins from 20 MeV to 28 GeV, @ variety of angles and positions.


> 300 cm2

@ 20 MeV>3000 cm2

@ 100 MeV>6400 cm2

@ 300 GeV

Energy-Range/ Effective Area

5.2.1

Particle Tests Relevant to Verifying the Requirement

Verification Method

ParameterTitleRequirement


LAT Science Requirements Verification Matrix (Examples)LAT Science Requirements Verification Matrix (Examples)


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• ACD – none

• TKR - one full size mechanical module and a four-tray module fully instrumented (3 with W and 1 bottom tray) with cables and electronic readout (mini-tower), TKR lift fixture, preliminary functional test scripts

• CAL – fully instrumented module, preliminary functional test scripts

• ELX/I&T - EGSE – EM1 version

• ME/I&T - 1 x 4 support grid

• SAS/I&T - GLEAM Monte Carlo, calibration algorithms

EM Deliverables to I&TEM Deliverables to I&T


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LAT Progress reportLAT Progress report-- Strengthening Plan and Prospect Strengthening Plan and Prospect --

Strengthening Plan:Technical management organization

• New technical management organization: Done [Klaisner, Chief Engineer; Horn, Sys. Engineer]• Closer collaboration with GLAST Project Office: Done• Selection of Spacecraft vendor: Done

Solution to major technical issues• Silicon Tracker bottom tray: In progress but will cost us a few months• ASIC production delay: May cost us one additional turn round• Delay in Crystal Detector Element of Calorimeter to be minimized

Definition of Engineering Model deliverables and delivery dates• Agreement between I&T and Subsystems near

Interfacing to Spacecraft• Close collaboration established and Interface Control Documents being worked out

Overall EM testing methodology and analysis • Yet to be worked out

Science analysis software• Preliminary plan formulated by joint LAT-SSC working group; recently peer reviewed

Prospect:Working hard to control schedule and budget within contingency.

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