The Glast Tracker Construction in Italy · The GLAST tracker construction The GLAST Gamma Ray Large Area Telescope GLAST is apair conversion telescope based on a 80mq Silicon tracker

Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa

The Glast Tracker Construction in Italy

Ronaldo Bellazzini

Space Part Meeting Elba Island, 14-19 May 2002


The GLAST tracker construction

The GLAST Gamma Ray Large Area Telescope

GLAST is a pair conversion telescope based on a 80mq Silicon tracker and a CsI Electromagnetic calorimeter directly derived from the high energy experiments.GLAST will explore the uncovered energy spectrum from 30MeV to 1TeV.

The tracker/converter is a very complex device, with about 1Milion readout channels, instrumented with single side silicon strip detectors. A modular design and the large use of industrial partners allow a fast and high quality construction.

http://glastserver.pi.infn.it look in presentations


Sources in Third EGRET Catalog

Launched in April 1991 Raised many interesting issues andquestions which can be addressed by a NASA mid-class mission (Delta II).

• Observed over 60 AGN in > 100 MeV gammas.

• About 1/2 dozen GRB at high energy.

• Measurement of diffuse gamma ray background to over 10 GeV.

• One hundred and seventy unidentified sources in 3rd EGRET catalog. Mystery of unidentifieds since 1970s

First Came EGRET


Map the High-Energy Universe

GLAST ScienceGLAST Science0.01 0.01 GeV GeV 0.1 0.1 GeV GeV 1 1 GeV GeV 10 10 GeV GeV 100 100 GeV GeV 1 1 TeVTeV

• Physics in regions of strong gravity, huge electric & magnetic fields: e.g. particle production & acceleration near the event horizon of a black hole.

• Use gamma-rays from AGNs to study evolution of the early universe.

• Physics of gamma-ray bursts at cosmological distances.

• Probe the nature of particle dark matter: e.g., wimps, 5-10 eVneutrino.

• Decay of relics from the Big Bang.

• GLAST pulsar survey: provide a new window on the galactic neutron star population.

• “Map” the pulsar magnetosphere and understand the physics of pulsar emission.

• Origin of cosmic-rays: characterize extended supernovae sources.

• Determine the origin of the isotropic diffuse gamma-ray background. dis

covery

reach

Are

a (s

quar

e cm

)

Energy (GeV)

GLAST

EGRET

0.01 0.1 1 10 100 10000.01 0.1 1 10 100 1000

1010

1010

1010

44

33

22

AGNSupernova Remnants


Pair-Conversion Telescope

GLAST ConceptLow profile for wide f.o.v.

Segmented anti-shield to minimize self-veto at high E.

Finely segment calorimeter for enhanced background rejection and shower leakage

correction.High-efficiency, precise track detectors located close to the conversions foils to

minimize multiple-scattering errors.Modular, redundant design.

No consumables.Low power consumption (580 W) Calorimeter

(energy measurement)

Particle tracking detectors

Conversion foils

Charged particle anticoincidence shield

γ

e+ e-

Photons materialize into matter-antimatter pairs: Eγ -> me+c2 + me-c2


The Large Area Telescope (LAT)

DAQ Electronics

Grid

Tracker

Calorimeter

ACD Thermal Blanket

•Array of 16 identical “Tower” Modules, each with a tracker (Si strips) and a calorimeter (CsI with PIN diode readout) and DAQ module.

•Surrounded by finely segmented ACD (plastic scintillator with PMT readout).

•Aluminum strong-back “Grid,” with heat pipes for transport of heat to the instrument sides.


TKR Flight-Tower Design & Assembly

Cable PlantUCSC

Tower Structure (walls, fasteners)Engineering: SLAC, HytecProcurement: SLAC. Italy

SSD Procurement, TestingJapan, Italy, SLAC

Electronics Design, Fabrication & TestUCSC, SLAC

Tower Assembly and TestItaly (18)

Tray Assembly and TestItaly

SSD Ladder AssemblyItaly

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

2592

10,368

342

648

34218


GLAST Tracker Design Overview

16 “tower” modules, each with 36cm × 36cm of active cross section

83m2 of Si in all, like ATLAS 11500 SSD, ~ 1M channels18 x,y planes per tower

– 19 “tray” structures•12 with 3% W on bottom (“Front”)•4 with 18% W on bottom (“Back”)•3 with no converter foils

– Every other tray is rotated by 90°, so each W foil is followed immediately by an x,y plane of detectors

•2mm gap between x and y oriented detectorsTrays stack and align to the side walls

The bottom tray has a flange to mount on the grid.Electronics on sides of trays:

– Minimize gap between towers– 9 readout modules on each of 4 sides Electronics

flex cables

Carbon thermal

panel

One Tracker Tower Module


SSD receiving (2200 SSDs up to now) and testing:•I-V curve•C-V curve•Dimensional test

Ladder assembly and test•Ladder assembly•Ladder bonding and encapsulation•I-V curve•C-V curve•Alignment measurement

Engineering Model construction•Tray assembly•Tray thermal and vibrational tests•Tower assembly

Status of the construction activities in Italy

Test status Total SSD

dimensional 1527

electrical 1450

electrical AND dimensional 1224

electrical OR dimensional 1744


Electrical • strips (p+) grounded / back plane (n) at variable V(+)• use calibrated instrumentations (Vsource,p-ammeter,LCR)• read through GPIB/LabView• data can upload DB automatically

IV scan 0-200VIleak at 150V

CV scan 0-200V Cbulk at 150VVdep with:2 fit intersectionHPK definition

SSD Pisa clean room measurements


Leakage current distributions

-600

-400

-200

0

200

400

600

800

1000

SW

X60

375

SW

X60

563

SW

X60

566

SW

X60

568

SW

X60

700

SW

X60

703

SW

X60

709

SW

X60

734

SW

X60

736

SW

X60

742

SW

X60

745

SW

X60

747

SW

X60

770

SW

X60

772

SW

X60

774

SW

X60

777

SW

X60

822

SW

X60

826

Batch

aver

age

leak

age

curr

ent (

nA

)

laboratorymanufacturer

Leakage current @ 150 V

0

50

100

150

200

250

300

350

0 20 40 60 80 100

120

140

160

180

200

220

240

260

280

300

320

340

360

380

400

420

440

460

480

500

Leakage current (nA)

Pisa

HPK@ Pisa @ HPK

Average 99.646 186.29

Min 40.083 79.720

Max 5450.6 618.79

RMS 191.19 60.385

1365 entries

batch analysis

all SSD


Bulk capacity ditributionsBulk capacitance @ 150 V

0

50

100

150

200

250

300

1800

1810

1820

1830

1840

1850

1860

1870

1880

1890

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

Bulk capacitance (pF)

Pisa

HPK@ Pisa @ HPK

Average 1837.3 1849.3

Min 1798.2 1749

Max 1906.0 2006

RMS 10.075 12.746

1375 entries

∆(th) ~ ∆C/C x (th) ~ 2 µm

1760

1780

1800

1820

1840

1860

1880

1900

SW

X60

375

SW

X60

563

SW

X60

566

SW

X60

568

SW

X60

700

SW

X60

703

SW

X60

709

SW

X60

734

SW

X60

736

SW

X60

742

SW

X60

745

SW

X60

747

SW

X60

770

SW

X60

772

SW

X60

774

SW

X60

777

SW

X60

822

SW

X60

826

Batch

aver

age

bu

lk c

apac

itan

ce (p

F)


batch analysis

all SSD


Depletion Voltage distributionsDepletion voltage

0

50

100

150

200

250

300

350

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

105

110

115

120

125

130

135

140

145

150

Depletion voltage (V)

Pisa

HPK@ Pisa @ HPK

Average 70.629 71.607

Min 35 40

Max 145 135

RMS 19.556 18.251

1375 entries

0

20

40

60

80

100

120

SW

X60

375

SW

X60

563

SW

X60

566

SW

X60

568

SW

X60

700

SW

X60

703

SW

X60

709

SW

X60

734

SW

X60

736

SW

X60

742

SW

X60

745

SW

X60

747

SW

X60

770

SW

X60

772

SW

X60

774

SW

X60

777

SW

X60

822

SW

X60

826

Batch

aver

age

dep

leti

on

vo

ltag

e (V

)


batch analysis

all SSD


Position of defects along SSD - all 1903 detectors

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1 14 27 40 53 66 79 92 105

118

131

144

157

170

183

196

209

222

235

248

261

274

287

300

313

326

339

352

365

378

strip number

numb

er of

defec

ts

Strip defects types

32

21

7

2

7

1

1

1

coupling short

strip isolation

poly-si resistor

implant short

ac-al open

implant open

strip open

leaky strip

HPK data statistics: defects analysis

bad strips/total strips=72/730752≈10-5


Shift= (∆yA+∆yD)/2Rotation=∆yA-∆yD

A

BC

D

305µm

200µm

300µm

• pixel/mm calibration on reference cross

• measure distance of reference cross centre to X and Y edge (all corners, ∆XA, ∆YA, ∆XB…)

• cut alignment evaluated with:

Geometrical

See http://glastserver.pi.infn.it/glast/lattd/ssd_insp_proc.doc (LAT-TD-00454)

SSD dimensional tests


Dimensions distributions

-6

-4

-2

0

2

4

6

8

10

12

SW

X60

375

SW

X60

562

SW

X60

564

SW

X60

566

SW

X60

568

SW

X60

570

SW

X60

572

SW

X60

699

SW

X60

702

SW

X60

708

SW

X60

733

SW

X60

735

SW

X60

737

SW

X60

743

SW

X60

746

SW

X60

769

SW

X60

771

SW

X60

773

SW

X60

776

SW

X60

778

SW

X60

825

SW

X60

827

SW

X60

829

SW

X60

837

SW

X60

923

SW

X60

927

SW

X60

929

SW

X60

936

SW

X60

948

SW

X60

968

SW

X60

971

Batch

aver

age

(mic

ron

)

shiftrotation

Shift and rotation

0

50

100

150

200

250

300

350

400

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

micron

Shift

Rotation

1527 15270.7 0.82.0 2.5

-11.0 -8.610.5 14.7

shift rotation

eventsaveragestdevmin

max

batch analysis

all SSD


13

5

3

2

1

high current

change in slope

chipped corners

damaged during lab test

high depletion voltage

24/1224 < 2% rejected

SSD failure analysis

Ileakage(120V)>500nA

Vdep>120V

probably due to transportation and handling

e.g. scratches, wrong applied bias


Ladder assembly

Alignment GlueingLadder assembly and testing activities in two qualified factories:G&A Engineering _ Oricola (AQ)MIPOT _ Cormons (GO)

Ladder = 4 SSDs glued together head to head without any mechanical support.All the pads are microbonded in series to form a unique detector 89.5mmX358mm


Alignment of ladders prototypes

Requirement: max SSD displacement ≤ 40µm

mechanical ladderswafers alignment errors

0

10

20

30

40

50

60

70

80

90

100

-50 -40 -30 -20 -10 0 10 20 30 40 50

µm

σ=5.5µmmin=-32µmmax=47µm

Ladder #A012

-20

-15

-10

-5

0

5

10

15

20

0 89.5 179 268.5 358

mm

µm

140 Ladders from mechanical wafersProduced by G&A Engineering for theEngineering Model Tower


• bonding pull strength between 6-9 gr. (measured at G&A and Mipot)

• bonding encapsulation (at G&A and Mipot):

pure epoxy(3M Scotchweld 2216 A/B)

dam (3M Scotchweld 2216 A/B )+ fill (General Electric 615 )

both good but dam&fill chosen as more reliable

MicroBondings and encapsulation


G&A ladder vs SSDs-sum leakage current comparison

-50

0

50

100

150

200

250

300

350

400

450

500

5 15 25 35 45 55 65 75 85 95 105

115

125

135

145

155

165

175

185

195

voltage (V)

curr

ent

(nA

)

LG001_ssdLG002_ssdLG001_encLG002_encLG001_bareLG002_bare

Mipot ladder #1 leakage current

0

100

200

300

400

500

600

0 25 50 75 100 125 150 175 200

Volt

nA

sum of SSD currents

ladder current

G&A (Scotchweld encapsulation)

Mipot (Dam&Fill encapsulation)

Ladders leakage current


Carbon-carbon closeout

• Trays are C-composite panels (Al hexcel core)

• Carbon-Carbon walls provide stiffness and the thermal pathway

from electronics to the grid.

Tray assembling

4x4 array of W foils


SuperGLAST tray without payload

The Engineering Model trays will be done with fully Carbon-Carbon closeouts, without the Al details

M2.5 thread holes F3 reference holes

M2.5 thread holes

Tray Assembly

Plyform, an Italian leading factory in composite assemby, has been qualified for tray production


0 50 100 150 200 250 300

X=-75mm

"X=+75mm"-0.02

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.02

Z(mm)

Y(mm)

X(mm)

tray GALST Plyform 0 bottom side

0 50 100 150 200 250 300

X=-75mm

"X=+75mm"-0.02-0.015-0.01

-0.0050

0.005

0.01

0.015

0.02

Z(mm)

Y(mm)

X(mm)

tray GALST Plyform 0 top side

X=-75mm

X=0mm

"X=+75mm"

Planarity of the GLAST tray #0 produced by PlyformVacuum bag differential pressure = 0.2Atm

Tray planarity


Tray #2 thermal boss profiles

-100

0

100

200

300

400

500

600

700

0 50 100 150 200 250 300 350 400

mm

µm

Trey #3 thermal boss profiles

-100

0

100

200

300

400

500

600

0 50 100 150 200 250 300 350 400

mm

µm


-100

0

100

200

300

400

500

600

700

0 50 100 150 200 250 300 350 400

mm

µm


-100

0

100

200

300

400

500

600

0 50 100 150 200 250 300 350 400

mm

µm

CMM measurements of the sides of the tray mean dimensions= 368.589 mmX368.586 mm+0.038

-0.034+0.066-0.037

MCM side

Close-out tolerances

Every other tray is rotated by 90°⇒it is very important to build square trays


bridge

handle

Z micrometers

guide

shoulder bridge pins

tray pins

Ladder assembly over the tray


Tool to assemble the ladders on the tray

Transfer bridge

Tool to glue the ladders over the tray

Prototype tray with dummy ladders


Tray 1 on the shaker

20. 2000. 40. 60. 100. 200. 400. 600. 1000.

30.

.1E-06

.1E-05

.1E-04

.1E-03

.001

.010

.1

1.

10.

Random Meas. channel

VT0111601IBTR RANDOM

RUN 10 RANDOM WITH NOTCH

T.P. 6 - MEASURE - CENTER - Z AXIS

Chan. No. : 6

Chan. type : M

DOF : 132

Level : 0. dB

Resolution : 4. Hz

Eng. unit : g

RMS (act.) : 42.6237 g

Contr. mode: Closed loop

-- Time on act. level --

Elapsed : 0:00:58

Remaining : 0:00:02

--- Time total ---

Elapsed : 0:02:33

Remaining : 0:00:02

Date : 9.10.2001

16:18:53

Marker x = 600 y(max) = 25.0348 Hz

g^2/Hz

0.013 g2/Hz

0.08 g2/Hz

Random vibration spectrum response (acceptance level)

NOTCHED @ 626Hz

20. 2000. 40. 60. 100. 200. 400. 600. 1000. .010

.1

1.

10.

100.

Sine Meas. channel

VT0111601IBTR INFN R

RUN 11 RES SEARCH AFTER RANDOM

T.P.6 - MEASURE - CENTER - Z AXIS

Chan. No. : 6

Chan. type : M

Sweep type : log

Sweeps done: 1

Sweeps tot.: 1

Sweep dir. : up

Sweep rate :2. Oct/min

Ctrl strat.: Average

Meas. mode : RMS

Eng. unit : g

Contr. mode: Closed loop

-- Testing time --

Elapsed : 0:03:25

Remaining : 0:00:00

Date : 9.10.2001

16:34:21

Marker x = 626.082 y(max) = 17.2844 Hz

g

ν1= 626 Hz Q ≈ 34

Normal modes search results.

FEM prediction=610Hz

Vibrational test


““EpoxyEpoxy” mock” mock--upup

Qualification-like test:• temperature range: -30°C ÷ +50°C• T0= 24°C• number of cycles: 4• 2 hr @ -30 °C, +50 °C• (dT/dt) = 0.5 °C/min

Tem

perature (°C)

∆L

/L (m

ε)

∆T=25 °C: ∆L/L ≈ 100 µε

∆T=-55 °C: ∆L/L ≤ - 350 µε

Thermal qualification cycles


““EpoxyEpoxy” mock” mock--upup

Maximum stress expected (∆T=25 °C):σ ≈ 12 MPa

∆T=25 °C: σ ≈ 11 MPa∆T=-55 °C: σ ≈ (-)26 MPa

Stre

ss (M

Pa)

∆T (°C)

28 MPa limit

Thermal test: results


Tower assembly- pre-Engineering Model test

Tower Assembly JigPre-Engineering Model Tower


GLAST Conclusions

Activity of GLAST-Italy started full steamon both hardware and software

The Italian Collaboration is providing critical contributions to:üLAT design and preparation for constructionü development of detector and science software

LAT prototyping (SSDs, ladders, tray construction, electronics, tower assembly) successfully concluded.2200 SSDs already received1200 SSDs tested

Next actions (july 2002):Assemby and test of 300 flight laddersConstruction of the Engineering Model


Software activity

I - Tracking

IV - GLAST simulation

VI - Construction and test software

II - Detector description

V - Test data analysis

III - Event display and graphics

Detector software - main areas of collaborations:


XML C++ generic model

Detector geometry in XML (GDD,detModel)unique description for recon, simulation, graphicsnow read by:•visualization tools•G4 simulation•prototype ROOT event display•Recon to be implemented


Software: on-going activities

Simulation LAT implemented in G4• interfaced to detModel (XML geometry description)• interfaced to a prototype ROOT event displayNext steps:• G4 validation (general, BT, BF)• interface with GAUDI• insert digitization modules

GLASTGLAST



Interactive event display•for simulation,

reconstruction, analysis•collecting user

requirements from whole collaboration

•candidates: ROOT (C++) and Wired2 (Java)

•ROOT event display for Balloon flight under

development



I - development of a reduced version of reconstruction package forlab-tests of stack of trays or a tower with cosmic rays

Software for construction and test

• Relational DB engine : MS-AccessØ easy programmingØ widely used in industry (no extra cost)Ø interface-able to most DBs – control softwareØ no data flow directly on the web

• Direct connection to laboratory instruments (LabView - Delphi using DDE protocol)• Procedure control (e.g. review of test non-conformancies) • Data selection (e.g. ladder selection)• Data analysis (VisualBasic + Excel)• Data security (MS-Access internal + WinNT network security)• read-only web interface (ASP queries + ODBC connection)• documentation at http://glastserver.pi.infn.it/glast

II – Construction Database


Construction DataBase architecture

central repository

Web client(ODBC)

Analysis Interface

Users desktops

Clean rooms

DAQ Interface

Selection Interfaceproduction and quality monitoring

Instrumentation(DDE)

data server

Data1 (SSD man)

Data2 (SSD lab)

Data3 (Ladders)Data1 Data2 Data3

Server interface

Data1 Data2 Data3

backup

input

I/O

Control Interface

output



Test data analysis• analysis of simulated data from BFEM and BTEMconfigurations for G4 validation studies

• preparation for BFEM data analysis

Tracking• study of charge sharing and signal generation to improve simulation

• study of TOT to improve vertexing

• angular accuracy study

• energy measurement from angular dispersion

Documents

The Glast Tracker Construction in Italy · The GLAST tracker construction The GLAST Gamma Ray Large Area Telescope GLAST is apair conversion telescope based on a 80mq Silicon tracker