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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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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.
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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)
laboratorymanufacturer
batch analysis
all SSD
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
)
laboratorymanufacturer
batch analysis
all SSD
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
• 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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Tray #4 thermal boss profiles
-100
0
100
200
300
400
500
600
700
0 50 100 150 200 250 300 350 400
mm
µm
Tray #1 thermal boss profiles
-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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
bridge
handle
Z micrometers
guide
shoulder bridge pins
tray pins
Ladder assembly over the tray
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
Tool to assemble the ladders on the tray
Transfer bridge
Tool to glue the ladders over the tray
Prototype tray with dummy ladders
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
““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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
““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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
Tower assembly- pre-Engineering Model test
Tower Assembly JigPre-Engineering Model Tower
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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:
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
Software: on-going activities
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
Software: on-going activities
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
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
Elba Space Part 18/5/2002 R.Bellazzini INFN Pisa
Software: on-going activities
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