The DØ Silicon Microstrip TrackerThe DØ Silicon Microstrip Tracker

Frank FilthautUniversity of Nijmegen / NIKHEF

NIKHEF, 4 August 2000

DD

4 August 2000NIKHEF

DDTevatron Run II UpgradeTevatron Run II Upgrade

Modification of Tevatron parameters:

Start of Run II: 1 March 2001

Aim: collect 2 fb-1 in two years (might be more…)

Switch from 396 ns to 132 ns bunch spacing at luminosity 1032 cm-2 s-1

Keep zero crossing angle for 396 ns operation; aim for 136 rad angle for 132 ns operationBeam spot: 35 m transverse, 25 cm longitudinal (10 cm for nonzero crossing angle)

Run 1

Run 2 (initial)

Run 2 (eventual)

Bunch spacing (ns)

3500 396 132

Luminosity (1031 cm-2 s-

1)

0.16 8.6 21

Interactions/crossing

2.5 2.3 1.9

4 August 2000NIKHEF

DDDØ Run II UpgradeDØ Run II Upgrade

Addition of central axial 2T magnetic field (SC solenoid in front of calorimeter cryostat)

Replacement of tracking system by combination of scintillating fibers (Central Fiber Tracker) and silicon sensors (Silicon Microstrip Tracker)

Central (CPS) and forward (FPS) preshower detectors

Extend muon chamber coverage to larger , smaller granularity

Upgraded calorimeter, trigger, DAQ electronics

Physics aims:

B-tagging based on b lifetime Improved electron and muon identification and

triggering Improved tau identification Charge sign determination

High pt central physics (tt, EW, Higgs and other searches): high multiplicity

Low pt physics (bb, QCD): requires good

forward coverage (e.g. lepton ID for || < 3)

4 August 2000NIKHEF

DDDØ Run II UpgradeDØ Run II Upgrade

4 August 2000NIKHEF

DDDØ Run II UpgradeDØ Run II Upgrade - Tracking - Tracking

ForwardPreshower

Silicon Microstrip Tracker Fiber Tracker

Solenoid Central Preshower

All share the same SVX IIe front-end electronics

4 August 2000NIKHEF

DD

1 2 3 4 5 6

1 2 3 4

5 67 8

9101112

SMT DesignSMT Design

Basic SMT Design:

Barrels F-Disks H-DisksLayers/planes 4 12 4

ReadoutLength

12.4 cm 7.5 cm 14.6 cm

Inner Radius 2.7 cm 2.6 cm 9.5 cmOuter Radius 9.4 cm 10.5 cm 26 cm

6 barrels 12 F disks 4 H disks

Axial strips to be used in 2nd level Silicon Track Trigger (STT) stringent requirements on alignment

Totals: 793k channels

3.0 m2 (of which 1.6 m2 DS)

4 August 2000NIKHEF

DDSMT DesignSMT Design

Layers 1 (3): 12 (24) DS, DM 900 ladders produced from 6” wafers (barrels 1 & 6: SS axial ladders from 4” wafers)

Layers 2 (4): 12 (24) DS 20 ladders produced from 4” wafers

SMT barrel cross-section:

Ladder count: 72 SS + 144 DS (900) + 216 DS (20)

4 August 2000NIKHEF

DDAnatomy of a LadderAnatomy of a Ladder

Ladders supported by “active” (cooled) and “passive” bulkheads

Ladders fixed by engaging precision notches in beryllium substrates on posts on bulkheads

Beryllium cools electronics expect chips to operate at 25 0C using

80% H2O/20% ethyl glycol mixture at –10 0C silicon should be at 5-10 0C

High Density Interconnect (HDI) tail routed out between outer layers

Carbon-fibre/Rohacell rails glued to sensors for structural stiffness

4 August 2000NIKHEF

DDSiliconSilicon

Significant fraction of silicon will undergo type inversion

Prefer high initial Vdepl for silicon at low radii

Specification of Vdepl, Vbreak

Selection of sensors at hand

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Calculated radiation dose as a function of radius (z=0):

Quality control at vendors & DØ institutes:

Ileak < 10 A at Vbias = Vdepl + 10V

20V < Vdepl < 60V

Polysilicon bias resistors: 1 M < Rbias < 10 M (DC bias pad)

Rinter-strip G Coupling capacitors: 10-15 pF/cm f(shorted cap’s) < 2% at min(Vdepl+15V,

90V)

4 August 2000NIKHEF

DDSensorsSensors

Need 144 sensors (2/detector)

Pitch: 50 m Typical Vdepl: 30 V All sensors delivered

by Micron Flatness problems

( 60 m) a concern

Single-sided

4 August 2000NIKHEF

DDSensorsSensors

Need 432 sensors (2/detector) Pitch: p-side 50 m, n-side 62.5 m Typical Vdepl: 20-40 V Slow sensor delivery by Micron

accepting sensors with higher Rbias

Double-sided 20

p-side n-side

4 August 2000NIKHEF

DDSensorsSensors

Need 144 sensors Pitch: p-side 50 m, 900 n-side 153 m Produced from single sensor (6” technology) Using DM layer, gang 2 n-side strips together to

form 1 readout channel Typical Vdepl: 50 V

Double-sided, double-metal

4 August 2000NIKHEF

DDSensorsSensors

Sensor delivery from Micron has been slow (30% yield) mainly due to p-stop defects on mask (noise affecting 10-15 strips) 5 sensors / week schedule problem, accepting few sensors with 1 p-stop defect

Double-sided, double-metal

4 August 2000NIKHEF

DDSensorsSensors

Need 144 sensors (12 detectors/disk) Pitch: n-side 62.5 m, p-side 50 m

(flexible pitch adaptor on n-side) Stereo angles: 150

Sensor delivery: Micron: delivered 125 sensors with reasonable

characteristics: Vdepl 60-70 V Eurisys: delivered 65 sensors:

First two batches: Vdepl 15-20 V, Vbreak 70-80 V Last batch ( 25 sensors) with better implants:

Vdepl 30-40 V, Vbreak 80-100 V

F-wedge

4 August 2000NIKHEF

DDSensorsSensors

Need 384 sensors (2/detector, 48 detectors/disk) Single-sided, glued back-to-back Pitch: 80 m Stereo angles: 7.50

Typical Vdepl: 60 V All sensors delivered by ELMA

H-wedge

4 August 2000NIKHEF

DDSVX IIe ChipSVX IIe Chip

SVX chip originally designed by LBL - FNAL for readout of CDF vertex detector, optimised for capacitances of 10-35 pF, ENC = 350e- + 50e-/pF

128-channel 8-bit digital chip, 1.2 m rad-hard technology

Both signal polarities Rise time set to integrate 99% of signal in 100 ns

(for 132 ns operation) Double correlated sampling for dynamic “pedestal”

subtraction Front end capacitor discharged during “beam gaps” Pipeline depth 32 max. 106 MHz readout speed (both edges of 53 MHz clock)

4 August 2000NIKHEF

DDSVX IIe ChipSVX IIe Chip

Daisy-chained readout of max. 9 chips Online sparsification using common threshold.

Modes: All channels Only above threshold Include 1 or 2 neighbours on either side (even if on

adjacent chips) Adjustable ramp rate (dynamic range) Power dissipation 5 mW/channel Unlike SVX III now in use by CDF, not deadtime-less

4 August 2000NIKHEF

DDHigh Density InterconnectHigh Density Interconnect

Two-layer flex-circuit mounted directly on silicon, housing SVX chips as well as passive electronics

Kapton based, trace pitch 200 m Connects to “low-mass” cable using Hirose

connector 9 different types for the 5 sensor types

2 for each sensor type except H disks 2 types for each ladder differ only in tail length

Laminated to beryllium substrate (total mass 0.041 X0, of which 0.014 X0 from Si)

Need 912 HDI’s

9-chip HDI H-wedge HDI

4 August 2000NIKHEF

DDProduction SequenceProduction Sequence

Probe Test Silicon Sensor

at Micron

Silicon Sensors

Test Bare HDI

Laminate HDI

Mount components on

HDI

Test stuffed HDI

Burn-in HDI

HDI

Build Ladder/Wedge Mount HDI on Silicon

Wirebond Detector

Burn-in Ladder

Laser Test

Build Full Wedge (H) Mount on Support

structure

Read out Detector

Probe Test Silicon Sensor

in house

“fail”

“fail”

Outside Co.

University

Fermilab

Micron

Eurisys

ELMA

Promex

Silitronics

Dyconex

4 August 2000NIKHEF

DDLadder Production in steps (9-chip)Ladder Production in steps (9-chip)

1. Apply pattern of non-conductive epoxy on p-side beryllium

2. Align beryllium with respect to active sensor, apply pressure and cure for 24 hr

3. Align active & passive sensors w.r.t. each other, apply wirebonds.

Then use separate fixture to position carbon-fibre rails. Use conductive epoxy to ground “passive” beryllium. Cure for 24 hr

4 August 2000NIKHEF

DDLadder Production in steps (9-chip)Ladder Production in steps (9-chip)

4. Use “flip fixture” to have n-side on top

5. Apply epoxy to n-side beryllium, fold over and secure HDI. Apply pressure and cure for 24 hr.

Then apply n-side Si-Si and Si-SVX wirebonds

6. Encapsulate bonds at HDI edges.

Connect “active” beryllium to cable ground

4 August 2000NIKHEF

DDTesting & RepairsTesting & Repairs

Bonds need to be plucked

- 50

0

50

100

150

200

250

0 128 256 384 512 640 768 896 1024 1152

mean

noise x10

diff . noise x- 1

Bad ground connection

Broken capacitors: cause SVX front-end to saturate, tends to affect neighbouring channels as well pluck corresponding bonds

Bad grounding of beryllium substrates causes large pedestal structures as well as high noise ensure RBe-gnd < 10

Repair broken / wrong bonds Replace chips / repair tails damaged during

processing

4 August 2000NIKHEF

DDBurn-in & Laser TestsBurn-in & Laser Tests

0

64

128

192

256

0 128 256 384

pulse height

Dead Channel

Laser

Laser Test: Energy just < Si bandgap

(atten. length 400 m test whole sensor)

Find dead & noisy channels

Determine initial operating voltages (from pulse height plateau, Ileak-V curve)

Burn-in Test:

Long-term (72 hr, 30’ between runs) test of whole ladder/wedge (conditions close to those in experiment)

x-y movable laser head

4 August 2000NIKHEF

DDOverall Quality (first half-cylinder)Overall Quality (first half-cylinder)

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Detector classification:

Dead channel: laser response < 40 ADC counts

Noisy channel: pedestal width > 6 ADC counts (normally < 2 counts excluding coherent noise)

Grade A: less than 2.6% dead/noisy channels

Grade B: less than 5.2% dead/noisy channels

Use only detector grades A,B; mechanically OK

Example for 9-chip detectors:

Dead Noisy

(better for other detector types)

4 August 2000NIKHEF

DDProduction Status and ProjectionProduction Status and Projection

Projected rates: assumed yield capacity

9-chip: 9.0/week 80% 15/wk 6-chip: 5.4/week 85% 10/wk H-wedge: 6.2 week 85% 10/wk F-wedge: 4.3/week 90% 15/wk

Yield Folded Detector Production

0

0.2

0.4

0.6

0.8

1

31-Mar-99 9-Jul-99 17-Oct-99 25-Jan-00 4-May-00 12-Aug-00 20-Nov-00

Date

Fra

cti

on

Co

mp

lete

9 Chip

3 chip

6 Chip

H disk

F Disk Nov 1, 00

Aug 10, 00

July 7

50% line

Rates include production, but in general dominated by sensor delivery.

However, HDI “stuffing” at Promex (9-chip) also a concern (wire bond pull strength, HDI bubbling during surface mount)

(as of July 7)

4 August 2000NIKHEF

DDBarrel Assembly in stepsBarrel Assembly in steps

1. Insert individual ladders into rotating fixture using 3D movable table

2. Manually push notches against posts (all under CMM)

Rule of thumb: Align to 20 m (trigger) Survey to 5 m (offline)

Precisely machined bulkheads Barrel assembly done inside out (protect wire

bonds)

4 August 2000NIKHEF

DDBarrel AssemblyBarrel Assembly

Layer 4 glued to bulkheads (providing structural stiffness, holding passive BH)

Thermally conductive grease applied (active BH only) for other layers

First 3 barrels assembled ( 4 weeks/barrel, excluding survey)

3. Secure ladder using tapered pins

4 August 2000NIKHEF

DDBarrel AlignmentBarrel Alignment

Shift d across ladder (3 m) Shift in radius (from ladder

flatness, better than 60 m) Rotation in ladder plane

(10 m 3 m) Rotation about short ladder

axis (70 m 4.6 m) Rotation about long ladder

axis (80 m 3.2 m)

Results for first barrel (similar for other two):

Should be OK for trigger purposes

Example: distribution for :

Note: relevant quantities are distributions’ RMS values (trigger accounts for average offsets)

4 August 2000NIKHEF

DDF-Disk AssemblyF-Disk Assembly

F-disk assembly less critical (not included in trigger), nevertheless performed under CMM

Quick process After assembly, “central” F-disk cooling rings

screwed onto active barrel bulkheads

z=0

Vdepl H H H HHHL ML L LM

Distribution of different quality devices over disks:

H/M = Micron high/medium Vdepl, L = Eurisys low Vdepl

4 August 2000NIKHEF

DDSupport CylinderSupport Cylinder

Double-walled carbon fibre structure supporting all but H disks (supported by CFT layer 3)

Split support (cut at z=0) introduced very late: gain 6 months of “schedule time” (installation can be done with end-cap calorimeter cryostats on platform)

First half-cylinder ready

4 August 2000NIKHEF

DDReadout ElectronicsReadout Electronics

For 5% occupancy, 1 kHz trigger rate: 1010 bits/s need error rate 10-15

Exercise readout system as much as possible before installation in experiment 10% system test using full readout chain (readout full F disk, barrel, barrel-disk assembly, H disk)

Complete readout chain (including L3 analysis, data storage) tested on several detectors

Monitoring Control

platformplatform

SEQ

SEQ

SEQ

SEQ

SEQ

SEQ

VRB Controller

Optical Link1Gb/s

VBD

V R B68k

Secondary Datapath

VME

3M

1553

NRZ/ CLK

IB

L3 HOST

ExamineExamine

HDI

Low Mass

4 August 2000NIKHEF

DD

Milestone Finish Date Completed

Barrel 1 Complete April 18, 2000 May 18, 2000Barrel 2 Complete May 23, 2000 June 13, 2000Barrel 3 Complete June 28, 2000 July 14, 2000Barrel 4 Complete July 27, 2000Barrel 5 Complete August 24, 2000Barrel 6 Complete September 22, 2000

F Disk 0 Complete March 28, 2000 March 31, 2000F Disk 1 Complete April 11, 2000 May 10, 2000F Disk 2 Complete April 25, 2000 May 23, 2000F Disk 3 Complete May 9, 2000 June 15, 2000F Disk 4 Complete May 23, 2000 June 30, 2000F Disk 5 Complete June 21, 2000 July 10, 2000F Disk 6 Complete July 6, 2000 July 19, 2000

F Disk 7 Complete July 20, 2000F Disk 8 Complete August 3, 2000F Disk 9 Complete August 17, 2000F Disk 10 Complete August 31, 2000F Disk 11 Complete September 15, 2000F Disk 12 Complete October 6, 2000

H Disk 1 Complete May 17, 2000H Disk 2 Complete July 7, 2000H Disk 3 Complete August 25, 2000H Disk 4 Complete October 16, 2000

South Half-Cylinder Complete and Ready to Move to DABJuly 27, 2000North Half-Cylinder Complete and Ready to Move to DABOctober 27, 2000

In preparation

Done

DoneDoneDone

Done

DoneDone

Started

Done

DoneDone

Started Half done

ScheduleSchedule

4 August 2000NIKHEF

DDCOSTWBS DESCRIPTION EST

1.1.1 SILICON TRACKER 7,857,0731.1.1.1 Engineering & Design 525,5411.1.1.1.1 SVX II engineering 157,5001.1.1.1.2 MOSIS submission 55,0001.1.1.1.3 UTMC submission 113,6001.1.1.1.4 HDI engineering 01.1.1.1.5 Test readout system 199,4411.1.1.2 Disks 1,407,5071.1.1.2.1 F disk 859,4851.1.1.2.1.1 F wedge detectors 539,3651.1.1.2.1.2 F wedge berylium 24,5801.1.1.2.1.3 Probe testing 51,9041.1.1.2.1.4 F disk fixtures 25,6951.1.1.2.1.5 F wedge fabrication 23,6041.1.1.2.1.6 F Disk Support 128,2921.1.1.2.1.7 F wedge det. spares 66,0451.1.1.2.2 H disk 460,9861.1.1.2.2.1 H wedge detectors 278,9501.1.1.2.2.2 Probe testing 12,0001.1.1.2.2.3 H wedge substrate 43,0611.1.1.2.2.4 H disk fixtures 19,7401.1.1.2.2.5 H wedge fabrication 44,0261.1.1.2.2.6 H Disk Support 63,2091.1.1.2.3 Spares 87,0361.1.1.3 Barrels 2,567,7361.1.1.3.1 Single Sided 218,1621.1.1.3.2 Single Sided Spares 284,8031.1.1.3.3 2 Degree 1,034,7471.1.1.3.5 90 Degree 395,3071.1.1.3.7 Probe Testing 209,6471.1.1.3.8 Berylium substrates 138,4501.1.1.3.9 Ladder Fixtures 47,0281.1.1.3.10 Barrel assembly fixtures 23,5231.1.1.3.11 Ladder fabrication 38,7911.1.1.3.12 Bulkheads 177,2781.1.1.4 Readout IC's 578,7241.1.1.4.1 F disk 155,9571.1.1.4.2 H disk 88,7441.1.1.4.3 Layer 1 27,7331.1.1.4.4 Layer 2 49,9191.1.1.4.5 Layer 3 55,4651.1.1.4.6 Layer 4 99,8371.1.1.4.7 Chip testing 37,8691.1.1.4.8 Spares 63,2001.1.1.5 Readout System (Detector to Port Card) 2,622,9831.1.1.5.1 Disk HDI 150,4191.1.1.5.2 Barrel HDI 347,4491.1.1.5.3 HDI assembly and test 344,2161.1.1.5.4 Low Mass Cables 682,0341.1.1.5.5 High Mass Cables 425,7361.1.1.5.6 Transition Card 113,4601.1.1.5.7 Bias Voltage System 80,6691.1.1.5.8 Interface board 479,0001.1.1.6 Mechanical Support, Services 114,5821.1.1.6.1 Half-cylinder 32,0001.1.1.6.2 Installation fixtures 10,0001.1.1.6.3 Cooling system 42,5821.1.1.6.4 Air system 10,0001.1.1.6.5 Monitoring system 20,0001.1.1.7 Detector Assembly, Installation 40,0001.1.1.7.1 Silicon install fixturing 15,0001.1.1.7.2 Silicon Supports 15,0001.1.1.7.3 Installation services 10,000

CostCost