1 j.m. heuser − silicon detector systems for cbm silicon detector systems for cbm johann m....

J.M. Heuser − Silicon detector systems for CBM 1

Silicon detector systems for CBMSilicon detector systems for CBM

Johann M. Heuser, GSI CBM meeting, University of Jammu, 14 February 2008

Silicon Tracking System

Micro Vertex Detector

Silicon Tracking Layer in MUCH ?

Overview ofTasks & environments

Detector technologies

System concepts

Technical challenges & prototyping


CBM – Electron-Hadron setupCBM – Electron-Hadron setup

RICH

TRDs ECALTOF

target

beam

PSDSTS +

MVD


MVD +

STS

MUCH

TRD TOF

target

beam

PSD

CBM – Muon setupCBM – Muon setup


Tracking of up to ~700 charged particles per event

Momentum determination with ~ 1% resolution

Interaction rate up to 10 MHz

Online r/o & reconstruction

Unprecedented challenge in this combination. New innovative system concept & technologies !

UrQMD,Au+Au, 25 AGeV

SSilicon T Tracking S System

Low-mass large-area, fast, Low-mass large-area, fast, radiation-hard detector system radiation-hard detector system

Task & EnvironmentTask & Environment


SSilicon TTracking SSystem

1 T dipole magnet1 m8 tracking stations

microstrip detectors: thin, passive, high spatial resolution

double-sided detectors (default)single-sided detectors in 16 stations: under study


amplifiers in r/o chip: pulse height pattern

Silicon Microstrip DetectorsSilicon Microstrip Detectors

Variety of constructions:

single-sideddouble-sided DC-coupled r/oAC-coupled r/ostrip lengths up to ~10 cm ...

n-

n+

p+

+ bias

("diode in reverse direction of operation")

MIP in Si: ~ 80 e-h pairs per µm track

charged particle

typically 300 µm

typically 50-100 µm h

e-

signal ~ 24k e-

++

-

-

Al


Detector ConceptDetector Concept

Layout of the tracking stations "sectorization"

sector = certain number of sensors read out together

Building block ("module")

Performance evaluation

Iterations of the layout

Implementation of realistic sensors, support, material, backed up by detector R&D

station 1, z=20 cmstation 8, z=100 cm

module

sector, made from 3 detectors

~ 1 m2


Detector OccupancyDetector Occupancy

microstrip detectors, 60 µm strip pitch, 7.5o angle front-back

fraction of fired strips per detector


2 projective coordinates in one thin silicon layer ( double-sided strip detectors)

readout electronics outside tracking aperture

ladder construction: electrical contacts at sensor's top/bottom edge

no "dead" region in the detector corners, (despite of stereo angle front/back strips)

radiation tolerance: design, material

Technical challenge: Technical challenge: Microstrip detectorsMicrostrip detectors CBM STS

tracking station

Detector module

readout direction

p side (front):"stereo" strips

blue: double metal connect-ions of strips I to III

n side (back): "vertical" strips"vertical" strips

I II

III

CBM01: R&D study GSI-CIS with focus on

Double-sided micro-strip detector, connectible at top and bottom row.


Microstrip detector Microstrip detector prototype, GSI-CIS, 8/2007prototype, GSI-CIS, 8/2007

4" wafer CBM01, 285 µm Si Test sensors

Double-sided, double-metal, 1024 strips per side, 50.7 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

Punch-through

biasing.

Polished float-zone Si.

I-V tests: Work as expected.

Addresses connectivity

Next iteration: radiation tolerance

Test board


Typical operation: about 6 years .

Situation:Interaction rate: 107/s Effective CBM run year:

2 months at full operation 5 × 106 s

Approaches:- Fluences estimated with URQMD generated events

- Fluence study with a FLUKA simulation of the CBM detector in its cave is ongoing

Estimated tolerance: ~ 1015 1-MeV neq

Challenge: Radiation EnvironmentChallenge: Radiation Environment

CBM cave

beam

STSdump

detector edge hit/cm2 part/cm2/6yr dose/6yr

STS @ 30cm inner 10 7.5·1014 20 Mradouter 0.25 1.8·1013 0.5 Mrad

STS @ 1m inner 1 7.5·1013 2 Mradouter 0.03 2.3·1012 60 krad

1 CBM-year assumed as: 2 month at 100% duty cycle 4 month at 50% duty cycle


Challenge: Combinatorial hitsChallenge: Combinatorial hits

microstrip detectors hybrid pixel detectors

1 central Au+Au event at 25 GeV/nucleon, tracking station at z=30 cm

compared with

track points : rec. points > 1:15 track points : rec. points 1:1

comb.hits

thin thick

true hits

Y [c

m]

X [cm]


Challenge: Tracking in STSChallenge: Tracking in STSCentral collisions Au+Au @ 25 AGeV

~ 1000 charged particles/event

~ 700 in aperture 2.5 – 25 deg

up to ~ 30 tracks/cm2 at z = 30 cm

required momentum resolution ~ 1%

effic

ienc

y [%

]

momentum [GeV/c]

Performance study of an 8-station STS:

Momentum resolution:

Track reconstruction efficiency:

includes cables, support(p > 1 GeV/c)

tracks [%]

primary, p > 1GeV/c 98.5

all, p>1 GeV/c 96.1

all, p> 0.1 GeV/c 90.4

3.2 % "ghost tracks"

Reconstructed central UrQMD event

XY

78 ms on Pentium 4 processor

XZ

"Cellular Automaton + Kalman Filter"

combinatorial hits

90 %


silicon sensorssilicon sensors + mech. frame

Momentum resolutionMomentum resolutionSTS with 8 microstrip tracking stations

400 µm Si per station

400 µm Si + 2 mm C ladder

400 µm Si + 2 mm C ladder + 2 mm Kapton

silicon sensors + mech. frame + r/o cables

[%]


material budget

Al-Kapton cables:

very thin (<50 µm total)

long high-density strip lines

50 µm pitch

low capacity (goal: S/N >10)

high-density interconnections

microstrip system

~20

- 60

cm

% X0

0.3

~1

.

.

.

.

>>1

r/o electronics

r/o electronics

Technical challenge: low-mass detector moduleTechnical challenge: low-mass detector module

1024 lines of 50 µm pitch: Cable length limited. to <10 cm.

1024 lines of 100 µm pitch: Two-layer cable → 50 µm eff. pitch. Length up to ~50 cm seem possible.


Pre-prototype of ultra-low-mass readout cable Pre-prototype of ultra-low-mass readout cable Cooperation with SESRTIIE Kharkov, Ukraine.

Structure: 55 cm length, 1024 lines, 100 µm line pitch

Material: 14 µm Aluminum on 10 µm Kapton

very challenging component

very challenging component


Challenge: Fast front-end electronicsChallenge: Fast front-end electronics High interaction rates: Require a data driven front-end.

n-XYTER chip 128 channels50.7 µm pitch

• dual polarity

• 30 ns peaking time

• ~1.4 ns jitter

• thresholds: > 2700 e

• count rates: ~160 kHz/strip

• token ring r/o scheme

• power: ~ 13 mW/ch

• 0.35 m CMOS

Used for CBM detector R&D: n-XYTER r/o hybrid for STS strip sensors.

Compatible with CBM DAQ board prototypes.

Lab and beam tests of STS.

Future:

Development of a new chip:

CBM-XYTER.

n-XYTER chip of the DETNI Consortium: Matches well CBM specs. Produced together with GSI.


Technical challenge: Technical challenge: Front-End Board & interconnectionsFront-End Board & interconnections

Future CBM-XYTER chip

detector/ readout cable

1024 channels per detector: 8128-ch readout chips

to ROC

FEB

r/o cable

sensor

~60 µm line pitch

Wire-bonding, tap-bonding of the thin fine-pitch structures?

~7 cm

FEB floor plan: how to arrange 8 chips in close distance?

50.7 µm


Challenge: System integrationChallenge: System integrationDetector module:

Electrical interconnections sensor-cable-FEE

Mechanical assembly of

- thin sensors + cables + front-end board

- on mechanical support frame.

Assembly steps single vs. double-sided module

Grounding/shielding

HV supply to sensors: through r/o cable, or extra cable?

Tracking system:MechanicsCooling of the fiducial volume? Insulation from hot FEE boards?

sensor

cable

FEE


MMicro VVertex DDetector

1 T dipole magnet1 m

2 vertexing stations

ultra-thin pixel detectors, very high spatial resolution

very low-mass mechanical support + thermal management

operated at sub-zero C temperatures in vacuum

Pioneering a fully novel, world-record thin detector system technique based on CMOS monolithic pixel sensors on diamond supports


Add-on to tracking: Precision decay vertex identification (D, c), spatial resolution few tens µm

Operational with at least 100 kHz interaction rate

Online charm trigger

New innovative system concept & technologies !


MVD - Task & EnvironmentMVD - Task & Environment

Ultra-low-mass, radiation-hard Ultra-low-mass, radiation-hard detector system detector system

782 rec. tracks2% ghost tracks

XZ

8 microstrip stations

MVD


MMonolithic A Active P Pixel D Detectors

Low-resistivity p-type Si hosting n-type charge collectors ("wells"):

signal created in epitaxial layer

Q ~ 80 e-h / μm signal < 1000 e−

charge sensed by n-well/p-epi junction

excess carriers diffuse towards diode

amplifier, CDS etc. on chip

thickness as thin as 50 µm

Cooperation with IPHC Strasbourg

pixel: 10 – 40 µm pitch

top view


100 kHz full-frame readout

Concept at IKF, University of Frankfurt

MVD R&D effort MVD R&D effort Radiation hard sensors > 1013 nequiv.

MVD demonstrator module

MAPS with column parallel readout

Material budget of full system: < 0.3% X0 or 300 µm Si

~ 5 cm

Potential MVD demonstrator station

at T= -20 C

ultimately:

Thin MAPS on thin industrial diamond support with integrated Al bus: 0.1-0.2 X0

(150 µm Si)R&D with IPHC & Fraunhofer


D (c = 312 m):D+ K-++ (9.5%)

D0 (c = 123 m):D0 K-+ (3.8%) D0 K- + + - (7.7%)

Ds (c = 150 m):D+

s K+ K- + (5.3%)

+c (c = 60 m):

+c pK-+ (5.0%)

c reconstruction: Greatest challenge!!

D0 z-vertex resolution

D+ reconstruction

Open Charm ReconstructionOpen Charm Reconstructionwith such a detector system ...


MVD +

STS

MUCH

TRD TOF

target

beam

PSD

CBM – Muon setupCBM – Muon setup


Track points in the first MUCH gap: similar to STS-8

10 MHz interaction rate

High radiation dose

Rather high granularity needed

No material budget limitNo material budget limit

Silicon pad detectors + fast self-triggered FEE. Under discussion.


MUCH-Si1 - MUCH-Si1 - Task & EnvironmentTask & Environment

Large-area (1.3 Large-area (1.3 STS-8), STS-8), fast, fast, radiation-hard detector system radiation-hard detector system

~ 1 hit/cm2/event(Geant study,

A. Kiseleva)

MUCH-Si1


Wafer thickness 525 µm

diode area 15 mm by 15 mm

Depletion voltage 100-120 V

Diode capacitance 37 - 41 pF

Bias for full depletion 20 V

Leakage current < 300nA total, <20nA/pad

Junction breakdown > 300V

Polysilicon bias resistor 1 M

from:

Proposal for a Nosecone Calorimeter (NCC) for the PHENIX Experiment

BNL, 3/2006 CBM01 wafer

Microstrip pad detectorsMicrostrip pad detectors

Area diodes; typical size ~ mm2 up to many cm2

Example: PHENIX pad detector prototypes (MSU/ELMA)

PHENIX pad detector prototypes

pad diode test structures, few mm2 area


sectorization study of 1st tracking station (zones of ~ same occupancy)

r = 0.8 m

sectors with 8 x 16 = 128 pads

possible "module"

(M. Ryzhinskiy)

Possible MUCH Si tracking stationPossible MUCH Si tracking station

# size pad size pad area sectors [cm x cm] [mm x mm] [mm2]

160 2.22 x 2.22 2.8 x 1.4 4

84 2.22 x 4.44 . .

64 4.44 x 4.44 . .

48 4.44 x 8.88 . .

28 8.88 x 8.88 . .

48 8.88 x 19.76 11 x 12.5 140

challenges:

• connection of r/o electronics to many SMALL pads

• check radiation env.

CBM-XYTER

— — From sectors to pads From sectors to pads ——

128 chs.


SummarySummaryCBM will comprise two, maybe three silicon detector systems

unprecendeted performance will be required

thin, fast, efficient/redundant, radiation hard: new/fully exploited state-of-the art technologies

challenge is especially in the system design

most important:

planning/evaluation in reliable simulation studies

characterization of prototypes from early on

STS: start to approach this phase simulation & prototyping

MVD: detector R&D active, system design/simulation mostly t.b.d.

MUCH-Si1: upcoming new activity, t.b. planned

1 j.m. heuser − silicon detector systems for cbm silicon detector systems for cbm johann m....

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