status of the silicon tracking system

J.M. Heuser − Status of the Silicon Tracking System 1

Status of the Silicon Tracking Status of the Silicon Tracking SystemSystem

Johann M. Heuser, CBM Collaboration Meeting, GSI, 28.2.2008

News and update on

Layout studies, realistic detector response

Radiation environment

Prototyping of detectors and components

R&D Cooperations, Tasks


STS detector layoutSTS detector layout8 stationsdouble-sided silicon micro-strip detectors, thickness 300m

Building block is a low-mass ladder structure

Support made of carbon boxes

Cables represented as capton boxes, thickness 200m

Readout electronics: thick layers of silicon and aluminium


Sectors: 6cm wide, 2 - 18 cm high

Station layoutStation layout

About 1.2 million channels total. Occupancy reaches 5.7% in central Au+Au collisions at 25 AGeV.

Station 1

Station 8

(R. Karabowicz)


Tracking resultsTracking results

OLD SETUP WITHOUT ADDITIONAL MATERIAL

tracking eff. 96.18 %

mom. resol. 1.3 %

NEW SETUP WITHOUT ADDITIONAL MATERIAL


mom. resol. 1.6 %

OLD SETUP WITH ADDITIONAL MATERIAL


mom. resol. 1.7 %

NEW SETUP WITH ADDITIONAL MATERIAL


mom. resol. 1.6 %

(R. Karabowicz)


Realistic detector response (I)Realistic detector response (I)

Sector view:Front strips in blueBack strips in greenMC points in circlesReconstructed hits: stars

Size of plot [cm]Position in STS:XYZ

Front strips’ ADC distributionBack strips’ ADC distribution

Simple Event Display

(R. Karabowicz)

so far: single strips underneath Geant hits activated

now: charge chared by several strips


Realistic detector response (II)Realistic detector response (II)

Problem:

wide, overlapping clusters in the most upstream stations

To be answered:

Do we require pixel detectors in the first STS stations?


Tracking results - incl. clusteringTracking results - incl. clusteringClustering included


mom. resol. 1.6 %

Work in progress: DIGITIZER: TOO SIMPLEHIT FINDER: TOO SIMPLE

Station 1 Station 8

(R. Karabowicz)


Radiation environmentRadiation environment

DPM

UrQmd

iFluka framework (D. Bertini) 1-MeV neutron equivalent fluences in CBM cave

(beam dump)

(interaction in target)


Radiation assessment in CBM (I)Radiation assessment in CBM (I)

per min. bias UrQMD event, 25 AGeV

(D. Bertini)


MUCH scoring planes

MDV+STS Scoring planes

Radiation assessment in CBM (II)Radiation assessment in CBM (II)


Dose in 6 years of CBM running:

~ 3 1014 nequiv.

Very Significant !!

Neutron fluence in STSNeutron fluence in STSSTS 5 STS 6

STS 7 STS 8

back scattering from MUCH absorber

~ 1 nequiv. per min. bias interaction

min. bias UrQMD @ 25 AGeV

(D. Bertini)


Ionizing dose Ionizing dose Calculated with GEANT for 6 years* of CBM running.

*1 year = 2 months at 107 int/s

Station 8, z =100cmStation 4, z =50cm

Station 1, z =30cm

comparable result with FLUKA

(R. Karabowicz)


Geometry composed of 28 stationsFirst station has vertical stripsSecond station has stereo strips 0.5 cm distance between stations.

Digitizer developedIdeal hit finder combining strips belonging to one track.Modified L1 tracking

STS built from single-sided strip detectorsSTS built from single-sided strip detectorsWhy to study

Technology "radiation hard" May be easier to construct

Tracking efficiency ~ 80 %no advanced features included (e.g. no computing speed optimization)

a b

a

b

First trials: (R. Karabowicz) (I. Kisel)


Microstrip detector Microstrip detector prototype CBM01, 8/2007prototype CBM01, 8/2007

4" wafer, 285 µm Si Test sensors

Double-sided, double-metal, 1024 strips per side, 50 µm pitch, 15º stereo angle, full-area sensitive, contacts at top + bottom edge, size: 5656 mm2

Double-sided, single-metal, 256256 strips, orthogonal, 50(80) µm pitch, size: 1414 (22 22) mm2

Main sensor

CBM01

CBM01B1

CBM01B2

Designed to explore CBM-specific connectivity


Towards 2Towards 2ndnd design iteration design iterationCIS activity in frame of german BMWI project INNOWAT -“SPID“

L. Long and R. Rolf, CIS

Test wafer to explore primarily

radiation tolerance

Full detectors

7 pixel detectors; 18 strip detectors.

Test structures:

3 Pad diodes, 4 Gate diodes,

6 PDTF, 2 SIMS, 2 SDM.

Process status 2/2008:

First active implant finished.

poly silicon bias structures


Characterization of CBM01 at CISCharacterization of CBM01 at CIS

IV and CV characterization of CBM01B1, CBM01B2, CBM02 (W. John et al.)

reported at CBM Meeting September 2007

U [V]

I [µ

A]

U[V]

I [µ

A]

U [V]

1/C

2 [p

F-

2]


Find application in various activities of Find application in various activities of beginning detector module R&Dbeginning detector module R&D

Only currently available CBM-specific microstrip detectors. Very important for STS prototyping!!

GSI: Test board (CBM01B2, preparation, report A. Lymanets)

Test beam tracking module (planned)

KINR Kiev: Pre-prototype module & CBM01B1 detector tests (electrical, diode laser, radioactive source) (report V. Pugatch)

Kharkov/JINR: Test board with microcable fanout structure (planned)

Cracow: n-XYTER-SUCIMA board with CBM01B2 (planned)

+ many new ideas around


Detector test board, GSIDetector test board, GSI

produced 2/2008

(A. Lymanets, J. Heuser)

test global detector characteristics

e.g. IV, CV

access both detector sides

contact a few strips for detailed measurements, including n-XYTER readout

do all this as quickly and as simple as possible to start work


DDetector module etector module pre-pre-prototypeprototypes, KINR Kiev s, KINR Kiev

CBM01-B1 detector:

p-side on test board

CBM01 detector, chip cable on carbon fibre support

(V. Pugatch)

J.M. Heuser − Status of the Silicon Tracking System 20 HV = 50 V HV = 70 V

Mapping of inter-strip charge charing with laser positioning system

CBM01-B1226 Ra from p-side, p-strips 5@6

CBM01 – first measurements at KINR CBM01 – first measurements at KINR

ES

trip

E Strip+1

0 10 20 30 40 50 60 700

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Voltage, V

Cu

rren

t,

A

VA - characteristic

Vitya (16.02.08 am)Sasha (21.02.08)V.O. (16.02.08 pm)

U [V]

I [µ

A]

Current-Voltage behaviour

(V. Pugatch)

Charge collection near surface

µm

ES

trip


Analog readout cable.

55 cm long, 1024 lines, 100 µm pitch55 cm long, 1024 lines, 100 µm pitch

14 µm Al on 10 µm Kapton14 µm Al on 10 µm Kapton

(V. Borshchov et al.)1024 strips50 µm pitch2 cm long

Readout cables, SE SRTIIE KharkovReadout cables, SE SRTIIE Kharkov

first pre-prototypes produced


R&D cooperations, tasksR&D cooperations, tasksISTC project:

“CBM Silicon Tracker“ (GSI, KRI St. Petersburg, MSU Moscow, IPHC Strasbourg)

HadronPhysics2 I3 JRA:HadronPhysics2 I3 JRA: 9/2007 9/2007Proposal: “Ultra-thin silicon tracking and vertex detection systems“

... decision in 2008 ...CBM STS Consortium: 2008 - 2010

JINR-SINP-KRI-SPbSU-SESRITIIE-BTI-(IHEP)-GSI

GSI R&D cooperations:

GSI-Kiev Inst. for Nucl. Research

Finnland: FAIR member, in-kind contribution to CBM

"single-sided rad-hard microstrip detectors"

project under preparation

To build and test a prototype(s) of the CBM STS Ladder


SummarySummarySTS still in conceptual design phase.

Progress with essential details, missing so far, is being made, including:

Realistic detector response (signal sharing, clusters)

Hit densities: - Strip technology in most upstream stations? - Are pixel detectors required?

Radiation study: How harsh are the operation conditions?

Deep consequences for the detector technologies and operating scenario.

Explore technologies: Double/single-sided strip detectors, AC/DC coupling...

Detector module concept: Very challenging design in mind, motivated by the low-mass requirement of our physics. Doable?

Risk management: Identify potential failures, redundant approaches, conservative and aggressive technical solutions.

Detector R&D: Essential. Becomes lively! Teams are forming. Preparations of test systems, test beams!

To aid this: Latest insights/results will be compiled in a technical document.

status of the silicon tracking system

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