Didier Ferrère, Geneva University Como, October 2001 1 The Construction Status of the ATLAS Silicon Microstrip Tracker D. Ferrère on behalf of the SCT

Didier Ferrère, Geneva University Como, October 2001

1

The Construction Status of the ATLAS Silicon Microstrip Tracker

D. Ferrère on behalf of the SCT collaborationDPNC, University of Geneva

General Description

Silicon Detectors

Electronics

Electrical Tests

Module Assembly

Summary & Status


2

Atlas at LHC

Atlas

LHC will provide protons and ions collisions

A designed luminosity of 1034 cm-2s-1

p-p collision with 14 TeV in the center of mass


3

The Atlas Detector


4

Physics Motivations

Simulated Event in the Inner Detector

•Higgs in SM and in MSSM

•Supersymmetric Particles

•B physics (CP violation, ...)

•Exotic physics

Requires a good tracking performance:

Secondary vertices

Impact parameters resolution

Track isolation

Measurement of high momentum particles


5

SCT Environment

23 overlapping interactions every bunch crossing (at the full Luminosity)

A bunch-bunch crossing every 25ns (40MHz)

Maximum equivalent 1 MeV neutron fluence after 10 years is ~ 2.1014 n/cm2

Operating temperature on silicon detectors is -7oC to contain the reverse annealing and the leakage current

Maintenance will likely require yearly warm-up of 2 days at 20oC and 2 weeks at 17oC

Material < 0.4 X0 at the outer SCT envelope

Operation in a 2 Tesla solenoid field


6

SCT in the Inner Detector

SCT:

•4 Barrels + 2x9 wheels

•4 different module types in the wheels

• < 2.5


7

The SCT Semiconductor Tracker

4 barrels9 wheels

9 wheels

5.6 m

1.04 m

1.53 m

4088 Modules

~ 61 m2 of silicon

15,392 silicon wafers

~ 6.3 million of readout channels

Barrel diameters:Barrel diameters:

B3: 568 mmB3: 568 mm

B4: 710 mmB4: 710 mm

B5: 854 mmB5: 854 mm

B6: 996 mmB6: 996 mm


8

The SCT module types

Barrel

2112 Barrel modules 2112 Barrel modules

936 Outer Forward Modules936 Outer Forward Modules

640 Middle Forward Modules (incl. 80 Short Middle)640 Middle Forward Modules (incl. 80 Short Middle)

400 Inner Forward Modules400 Inner Forward Modules


9

Module Pictures

A Barrel Module

• 2 daisy chained detectors / side• The Kapton hybrid is bridged over the detectors• The cooling pipe is on the connector side

An Outer Forward Module

•2 daisy chained detectors / side• The Kapton hybrid is at the far end• The cooling area is common with the mounting blocks


10

Silicon Detector Pictures

Scratch pads for identification – Corresponds to DB serial number

Barrel Pitch : 80 m

Forward Pitch:

•W31 and W32: 161.5 rad

•W12, W21 & W22: 207 rad

1 Barrel detector type

5 Forward detector types:

W12: Inner Module

W21 & W22: Middle Module

W31 & W32: Outer Module

Single sided p-in-n detectors

285 m thickSize ~ 6x6 cm2

768 strips


11

Detector Delivery in Geneva

020406080

100120140160180

Mar-01 Apr-01 May01 Jun-01 Jul-01 Aug-01

Month

Det

ecto

r n

um

ber

Total

W31

W32

Silicon Detector Status

Total ordered: 2500Delivered: 570Rejected: 4% delivered: 22.64

Delivery status of Hamamatsu Delivery status of Hamamatsu detectors in Geneva Universitydetectors in Geneva University

The detectors passed the Production Readiness Review in August 2000. The production delivery started this year.

Manufacturers Hamamatsu

(Japan)

CiS

(Germany)

Sintef* (Norway)

Contribution 79% 17% 4%

Sensor types All Wedges Barrels

* On going qualification

The detector purchases is distributed as followed:


12

Silicon Detector – Some SpecificationsTotal leakage current at 20 oC: <A@150V and <2A@350V

Leakage current stability: to increase by not more than A @150V in dry air over 24 hours

Depletion Voltage < 150V

R bias = 1.25 +/- 0.75 (Poly-silicon or implanted technology)

C coupling >= 20 pF/cm @ 1kHz

C interstrip < 1.1pF/cm @ 100kHz @ 150V bias

R interstrip >2x R bias at operating voltage

Strip metal resistance <1/cm

Strip quality: a mean of >99% good readout strips per delivery batch. Not less that 98% /detector

Total leakage current <250 A up to 450V @ -18 oC

Leakage Current stability:to vary by no more than 3% in 24 hours at 350V at -10 oC

Strip defects: Number of strip defects (dielectric & metal) within pre-irradiation acceptance level

Charge collection: Maximum operating voltage for >90% of maximum achievable charge : 350V

Pre-Irradiation

Post-Irradiation


13

Silicon Detector Quality Control

Example of W31 normalized current @ 20oC

Quality Control consists of systematic checks for Visual Inspection and IV scan & sub-sample tests (10% of the detectors): Depletion voltage, full strip test, metal strip resistance and Interstrip capacitance

Up to now only few rejections has been made based on visual defects and extra currents.

nA


14

Silicon Detector Quality Control

W32 - Defect strips

020406080

100120140160

0 2 4 6 8 10 12 14

# of bad channels

# o

f d

etec

tors

W31 - Defect strips

0

2040

60

80

100120

140

0 2 4 6 8 10 12 14

# of bad channels

# o

f d

etec

tors

02468

10

-1 4 9 14

0

2

4

6

8

10

0 2 4 6 8 10 12 14

0.082 % of detective strips out of 172 detectors

0.044 % of detective strips out of 170 detectors

The defective strips are identified by Hamamatsu and the QC at the Institutes. The full strip test allows to identify all possible defects like:

Open, Short, bias resistor break, pin hole, oxide punch through, implant break.

The detectors are slightly biased during the measurement and up to 100V DC is put on the strips.

LCR meter allows to measure coupling capacitance and the relative bias resistor.

Hamamatsu series production delivered in Geneva


15

Silicon Detector – Irradiation

The detectors are irradiated using 24 GeV protons at CERN PS.

All strips are grounded and the backplane is biased to 100V during the irradiation.

Typical annealing is done at the minimum of the beneficial and reverse annealing.A

V


16

Silicon Detector – Charge Collection after Irradiation

BarrelBarrel

W31W31

W32W32

350V

The detectors were annealed 7 days at 25oC after an irradiation of 3x1014 p/cm2

The readout was made with SCT 128A chips (DMILL technology). A Ru106 source was used for the injected charge.

The Signal to noise ratio is for a strip length of ~6 cm

The measurement was taken at –18oC

A S/N plateau around 17:1 is A S/N plateau around 17:1 is reached above 350V for all the reached above 350V for all the Hamamatsu detectorsHamamatsu detectors

Similar results are obtained for the Similar results are obtained for the other detector purchasesother detector purchases

D. R

obinson


17

The Front End Electronics

Binary ABCD chips are based on DMILL BiCMOS technology

•Noise with detectors (12 cm strips): < 1500 e-

•Efficiency: 99%

•Occupancy due to Noise : 5x10-4

•Double pulse resolution: 50ns for 3.5fC following 3.5 fC signal

•Shaping time ~ 20 ns

•Pipeline Length: 3.2 s (128 locations)

•Functionality temperature range: -15 to 30oC

•Power dissipation: < 3.8 mW/channel

•Specified total radiation dose: 2x1014 n/cm2

10 Mrad


18

The Front End ElectronicsABCD 3T – Trimming function

The readout chips passed the PRR in July 2001.

Pre-series have started with 35 wafers already delivered. In November 200 wafers are expected. The measured yield on the pre-series is spread from 10 to 50 % and the expected yield in average is ~26%. ATMEL think they can improve it!

The wafer screening for the Quality The wafer screening for the Quality Control will be done at 3 places: Control will be done at 3 places:

CERN, RAL and SCIPP.CERN, RAL and SCIPP.

Yield consideration based on:• All analog and digital functionalities are OK (tested with threshold, bias and frequency scan)• No Icc or Idd problem• No bad channels

Current testing time ~9 hours/waferWill be decrease during prod by a factor 2


19

The Module Test Set-up

VME

NationalInstrumentsPC-VMEInterface

CLOAC:Generates masterclock, trigger andreset

SLOG:Generates slowcommands, mergeswith fast commands

CLOACFANOUT

MUSTARD:Receives anddecodes data

OPTIF:Bi-phase MarkEncoding + opticaldata receiver

SCTHV:High Voltagepower supply

SCTLV:Low Voltagepower supply,merges with HV

Conventional Cable (30m)

Thickpowertapes(~4m)

PPB2

PPB1

Thinpowertapes(~1.5m)

Opto-harness

ATLAS-SCTDetector Module

Temperature andHumidity Probes

~25m opticalfibres Tests on modules:

• Measured gain curve (with internal calibration signal)

• Hit occupancy versus comparator threshold without signal (“Noise Occupancy”)

• Determination of ENC (from response curve and Noise Occupancy)

•Pulse shape through variation of calibration pulse delay

• Power consumption at different settings

• Various digital function checks (pipeline & data transfer)

The SCT DAQ (software and hardware) readout test set-up is the same in all the laboratories.


20

Signal and ENC determination

“S-curves”:

• Measure hit occupancy as a function of the threshold

• Fit error function to occupancy “S-curve”

• Determines mean signal & rms


21

Module Performances

5x10-4

Pre-irraditionPre-irradition

• ENC noise: ENC noise: 1400-1500e-1400-1500e-

• NO @1fC: NO @1fC: 1-2 x 101-2 x 10-5-5

Post-irradition Post-irradition

• ENC noise: ENC noise: 1900e-1900e-

• NO @1fC: NO @1fC: 2-3 x 102-3 x 10-4-4 * *

* Acceptance criteria : 5x10* Acceptance criteria : 5x10-4-4


22

KEK Test Beam – Median Charge

Preliminary results from N. Unno

Barrel and End-cap modules are functioning Barrel and End-cap modules are functioning well and are very similarwell and are very similar

A small difference between barrel and end-cap modules is observed and could be due to:

Larger effective pitch for the forward and less charge sharing.

(V)


23

KEK Test Beam – Efficiency and Noise Occupancy

Preliminary results from N. Unno

Specs


24

Test Beam Results – Spatial Resolution

Gives spatial resolution in Gives spatial resolution in X/Y X/Y

• (X) = 20(X) = 20mm

• (Y) = 750(Y) = 750mm

Spatial resolution in strip Spatial resolution in strip coodinate (+/- 20mrad coodinate (+/- 20mrad stereo angle)stereo angle)

2323mm

compatible with digital compatible with digital resolution for 80resolution for 80m pitchm pitch


25

Multiple Modules in the System Test

Determine performance of individual modules

Measure noise and “inter-module” effects

Optimize grounding and shielding in realistic setup


26

Noise Performance in the System Test

Tests on multi-modules barrel setup


27

Noise Comparison System Test versus Single Module Test

ENC System Test ENC Individual Module ENC Noise Occupancy


28

Module Assembly

Parallel module production will take placeBarrel: KEK, RAL, LBL, Oslo – Starting at the end of this year

Forward: Freiburg, Geneva, Melbourne, Nikhef, MPI, UK-North, Valencia

Aligned forward detector pairs onto transfer plates

Barrel alignment system


29

Module Mechanical Tolerances

SCT Philosophy:SCT Philosophy: Build modules to a sufficiently high tolerance that alignment corrections “within the module” are not needed for track reconstruction

Physics requirement:Physics requirement: Alignment accuracy rms (in micron)

Direction (cyl. Coord.)Direction (cyl. Coord.) BarrelBarrel ForwardForward

R 100 50

12 12

z 50 200

Internal module build tolerances:Internal module build tolerances: Alignment tolerance (in micron)

BarrelBarrel ForwardForward

XY wafer to wafer plane in 1 plane 4 4

XY back to front plane 8 8

XY relative to mounting holes 30 20

Z surface of silicon detectors 40 100


30

Engineering

Forward disc sectorMiddle cooling circuits, cooling

blocks and low mass tapes

Barrel sector close-up view ofbrackets, pipes, modules…

Barrel support structure is Barrel support structure is under constructionunder construction

Forward support structure is Forward support structure is ready for FDRready for FDR


31

Summary and Status

Detectors• The series production started beginning of 2001 and is well on the way• ~ 36% of the detectors are delivered and the quality is very good

Chips

• ABCD3T passed production readiness review and first lot of production wafers

are expected soon

Modules

• Barrel modules passed FDR and will start production at the end of the year

• Forward modules require 1 more round of hybrid production before going to FDR

Engineering, Off-detector Components, power distribution

• A series of FDRs started in spring

• First parts are/will be soon order for production


32

Appendix - Typical Power Consumption

Before Irradiation After Irradiation

Idd (mA) 550 750

Vdd (V) 4.0 4

Icc (mA) 950 560

Vcc (V) 3.5 3.5

Power (W) 5.2 5

ICC after irradiation due to the optimization of the FE setting:• before irr: Ipre = 220 A and Ishap = 30 A• after irr: Ipre = 150 A and Ishap = 24 A

Module current and powerModule current and power


33

Appendix – Prototype Components of the Forward Modules

Spine

Kapton Hybrid


34

Appendix – Optical Links

Opto-packages on the dog-leg (Barrel)

Forward Opto-plug-in:PIN receiver (Clock & Control BPM) &2 VCSEL lasers for data links


35

Appendix – Forward Electrical Performances

From

G.M

oorhead


36

Appendix – Forward Electrical PerformancesF

rom G

.Moorhead


37

Appendix – Thermal Simulation

Requirement:Requirement: Prevent Thermal Runaway

Facts of life: Leakage current (4 detectors of the module) after 10 years in the LHC reaches ~2mA @ 500V @ -10 C (spec: <1. 0mA @450V @- 18 C) Increased ASIC power estimates: now 6.8W per module ASICs are close to detector and module designs are optimized to limit heat transfer to detectors.

Some thermal design features: Baseboard or spine are made of TPG (Thermo Pyrolitic Graphite). Conductivity: 1700 W/ m/ K along length Improved hybrid substrate (metallised CF or CC) reduces hybrid & ASIC temperatures, reducing convection (~ 0.5W with CF) Evaporative C3F8 cooling - extensive system prototyping has been done. It looks promising using -20 C at the cooling block


38

Appendix – Thermal Simulation


39

Module Power Consumption

0

200

400

600

800

1000

1200

1400

0 20 40 60

clk [MHz]

Idd

[m

A]

Idd(B037 mA)

Idd(B020 mA)

Idd(B017 mA)

After annealing

(10 days continuous warm operation)

• observed on some modules increase of Idd current (up to x2 normal current) but still within specs for current and total module power (6.8W/module)

• on effected module current comes from all chips uniformly

• under investigation ...

@ 40MHz

Documents

Didier Ferrère, Geneva University Como, October 2001 1 The Construction Status of the ATLAS Silicon Microstrip Tracker D. Ferrère on behalf of the SCT