25/9/2006dmitri tsybychev stony brook1 vertex 2006 perugia, italy september 24-29, 2006 dØ silicon...

25/9/2006 Dmitri Tsybychev Stony Brook 1

Vertex 2006Perugia, Italy

September 24-29, 2006

DØ Silicon Detector and Experience at Tevatron

D. Tsybychev (Stony Brook)On behalf of DØ collaboration


• Outline:• Overview of Tevatron and DØ

experiment• Layer 0 concept • Layer 0 commissioning and

preliminary performance• SMT status• Summary and outlook


The Tevatron

Proton-Antiproton collider √s = 1.96 GeV Ultimate peak luminosity 3x1032

cm-2 s-1

Expecting to accumulate 8 fb-1 by 2009

Good data taking efficiency ~ 85%


DØ DetectorCentral Scintillator

Forward Mini-drift chamb’s

Forward Scint

Shielding

Tracking: Solenoid(2T), Silicon,

Fiber Tracker

Calorimeter

Central PDTs

5

SMT Design

Barrels F- Disks H- Disks

Channels 387072 258048 147456

Modules 432 144 96

Si Area 1.3 m2 0.4 m2 1.3 m2

I nner R 2.7 cm 2.6 cm 9.5 cm

Outer R 9.4 cm 10.5 cm 26 cm

108.1 cm

6 barrels

12 F-disks

4 H-disks

4 super-layers in barrelL1in, L3in: DSDM,

90o stereoL1out, L3out: single sidedL2, L4: DS, 2o stereo

6

DØ Layer 0Mitigates tracking losses due to radiation damage to Layer 1 of SMT detectorImprove IP resolution, especially for low pT tracks

Less material at first silicon hit 1st Tracking hit closer to IP

Layer-0 Physics Gains Proper Time Resolution

= 105 fs (SMT) 75 fs (layer-0, no layer-1)

b-Tagging efficiency gain ~15%


Where does L0 go?

Very tight space constraint outer radius ~23mm inner radius ~15mm


Layer 0 installed inside SMT in April 2006


Layer 0 detector The detector consists of:

48 modules mounted on carbon fiber support structure

6 -segments, 8 z-segmentsFour sensor types provide 98.4% of acceptance

Sensors 12 and 7 cm lengths

71 and 81 micron pitch with intermediate strips

Signals transferred to readout chips using low mass analog cables

11

Layer 0 Module

hybrid

analog cablesensor

Double-deck analog cable between sensor and hybrid• 91 m pitch, shifted by half

pitch • 17, 24, 32, 34 cm long

SVX4 readout chip

SVX4

pitch adapter

12

Silicon Readout Data Flow

PlatformPlatform

SEQ

SEQ

SEQ

SEQ

SEQ

SEQ

MCH2MCH2

3/6/8/9 Chip HDI

Sensor

8’ Low Mass Cable

~19’-30’ High Mass Cable (3M/80 conductor)

Optical Link1Gb/s

V

R

B

C

V

B

D

V

R

B

PwrPC

SDAQ

VME

HV / LV

1553 Monitoring

25’ High Mass Cable (3M/50 conductor)

CLKs CLKs

Serial Command Link

PDAQ (L3)MCH3MCH3

PwrPC

1553

CathedralCathedralHorse ShoeHorse Shoe

Adapter Card

KSU

Interface Board

SEQController


SMT and Layer 0 Electronics infrastructure

DAQ must accommodate both SVX2 and SVX4 Isolated power for SVX4 SVX4 readout chain after IB (new for Layer 0)

digital jumper cable junction card: impedance matching twisted pair cable adapter card

SVX4 voltage regulation differential (SVX4) single ended (existing system) Ground isolation

Layer 0 HV Upgraded Sequencer and Sequencer Controller

firmware to accommodate coexistence of SVX2 and SVX4


Junction cards

Digital Cables

LV/HV cables

ClocksTwisted pair cables


The Big Challenge – Noise

The most difficult challenge (in terms of electronics) for detectors of this type is to reduce noise

Analog cable works as a “good” antenna

Noise Sources Ground Loops

Continuous carbon fiber structure Electronics at both ends

Power Supplies Noise Other Noise conducted into the

detector Capacitive coupling is very

important

poorly grounded DØ prototype module total

noisediff. noise


Noise elimination – Layer 0 implementation

Electronically create an isolated ground on the detector

Dedicated adapter card Use ground isolated power

regulators near the detector All signals sent differentially across

the barrier CLC filter before regulators, for

SVX4 power Isolated high voltage ground with 10K resistorIsolated ground needs reference to the outside world

This is provided by the high voltage ground resistor

Mesh spacer to minimize capacitance between analog cables

analogcable

pitchadapter

meshspacer wrap-around

bumpers

17

Other Tricks

Carbon fiber cocured with flex circuit with copper trace to achieve better contactGround pads at backplane of hybridWrap-around to connect sensor GND to support (as well as bias voltage to backplane)

ground for hybridground for hybridwrap-around for wrap-around for ground and biasground and bias


pedestal total noise 10 diff. noise 10

Test standWithout filters With filters

Installed in DØ


Noise Performance

Outstanding noise performanceTypical noise with bias

~1.7 ADC S/N ~ 18

Pedestal peak-to-peak difference

4-5 ADC counts – acceptable

Important for online readout occupancy i.e. deadtime. Typical chip threshold 3 * (~6 counts) above pedestal

pedestal total noise 10 diff. noise 10


Performance - Charge Distributions

More one stripClusters than MC

Better simulation of charge


Hit Finding Efficiency

Efficiency somewhat lower in data


CDF Layer-00 (L00)

Single sided layer of Silicon

Radiation hard 50 micron readout strip

pitch Low Mass: 0.6%-1.0% X0

Mounted directly on Be beam-pipe

6 narrow (r=1.35 cm) and 6 wide (r=1.62 cm) φ segments12 sensors along z (94 cm)

2.3cm

4.2cm

Be Beam-pipe

Sensors

SVXII Inner bore

Cooling channels

300m installation clearance

72 Ladders / 108 chips


CDF L00

cable1 cable2

Signal Cables

Narrow Sensors

Wide Sensors

Hybrids

Large coherent noise: Continuous pattern

across all strips on a sensor

Induced by silicon readout

Different event by event Coupling between cables

Not usable for trigger


CDF L00

Read all the channels Do pedestal subtraction offline

Pedestal fit Event by event fit to find the

pedestal distribution Ignoring sharp peaks: real

clusters Effectively finds clusters

Makes a huge difference in B physics

without L00 with L00


L0 Alignment

Pull of the hit residiuals Residual =

expected hit position – actual position

Default geometry based on the survey data from detector assembly

26

Impact parameter resolution with L0

Impact parameter resolution with Layer 0 30 % improvement

Better for low Pt tracks

Magnet off data with cosmic muons

27

CurrentsLayer 0 VI Curves

1.00E-08

1.00E-07

1.00E-06

0 100 200 300 400 500 600 700 800

Voltage

Cu

rren

t

Layer 0 currents have been rising slowly since turn-on• Initial currents were tiny < 100 nA/detector• Expected current rise due to radiation ~1.8 A• Jumps between stores in some detectors.These types of detectors are known to be sensitive to surface charge and operation in low humidity.Essentially identical to LHC sensors


SMT StatusEnabled ~50 HDI (125 were disabled)Some previous problems reoccur

Typical failure modes: No download, chip

failures, DVDD trips, no readout, high leakage current

Reasons not fully understoodDetector is not accessiblePart of readout chain in collision hall

Connections Cables SVX2 Ageing?

Repair work during shutdown

1 J

an

, 20

06


F-disk Noise “Grassy”

noise“Grassy” noise appeared after a several months of operationOnly p-side of fraction of the Micron sensor Looks like micro-discharge

Charge-up effect observed

300

200

100

20

10

0

Micron sensors Eurysis sensors

Beam on

Beam on

Beam off

Beam off


Before Shutdown After Shutdown Comparison


SMT Performance

p-side pulse-height (ADC)

for a MIP

S/N

(tota

l) r

ati

o

10

15

9p 9n 6p 6n 3

Heavy flavor tagging

Vertex resolution

(cm)

0.01


Summary and Outlook

New Layer 0 for DØ silicon detector Installed in April 2006 and fully operational Error free readout Exceptional noise performance Very few bad channels Already see improvement in tracking of

charged particles at DØ

Pursuing broad physics program

25/9/2006dmitri tsybychev stony brook1 vertex 2006 perugia, italy september 24-29, 2006 dØ silicon...

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