1 J.M. Heuser CBM Silicon Tracking and Vertex Detection System Development of a Silicon Tracking and Vertex Detection System for the CBM Experiment at

J.M. Heuser CBM Silicon Tracking and Vertex Detection System 1

Development of a Silicon Tracking Development of a Silicon Tracking and Vertex Detection System and Vertex Detection System

for the CBM Experiment at FAIRfor the CBM Experiment at FAIR Johann M. Heuser, GSI Darmstadt, Germany

for the CBM Collaboration

VERTEX 2006, Perugia, Italy, September 2006

The international FFacility for AAntiproton and IIon RResearch

The CCompressed BBaryonic MMatter experiment

The Silicon Tracking and Vertex Detection System:

Performance requirements, Detector concept, R&D activities


FFacility for acility for AAntiproton and ntiproton and IIon on RResearch esearch @ GSI Darmstadt @ GSI Darmstadt

existing GSIexisting GSI

FAIR FAIR 20152015

Observers:Observers:

Start of construction: 2007/2008

staged commissioning: 2011-2014Full operation, CBM: 2015

International project:International project:


Five Research Communities at Five Research Communities at FAIRFAIR

100 m

High EM FieldHigh EM Field (HI) _Fundamental Studies (HI & p)Applications (HI)

Plasma Physics: Plasma Physics: x600 higher target energy density 600kJ/g

Nuclear Matter PhysicsNuclear Matter Physics withHI beams, 35-45 GeV/n, x1000

Hadron PhysicsHadron Physicswith antiprotons 0 - 15 GeV

HESR

SuperFRS

NESR

CBMCBM

FLAIRCR- RESR

Rare Isotope Prod. Target

AntiprotonProd. Target

Nuclear Structure & AstrophysicsNuclear Structure & Astrophysicswith radioactive beams, x10 000and excellent cooling

SIS-100, SIS-300

U 35 GeV/n p 90 GeV

Heavy-ionsynchrotrons

Ion source

Unilac

SIS-18


Compressed Baryonic Matter-Experiment Compressed Baryonic Matter-Experiment

SIS-300: up to U92+,15-35 GeV/nucleon, beam intensities up to 109/s,

Z/A = 0.5 nuclei up to 45 GeV/nucleon

→ exploration of the QCD phase diagram with heavy-ion collisions!

→ investigation of nuclear matter at highest baryon densities but still moderate temperatures in A+A collisions


Milestone in mapping the QCD phase diagram would be the (unambiguous) discovery of either the critical point or the 1st order phase transition

Top-energy SPS, RHIC, LHC :

high T, low B region –

most probably phase crossover

High B region ! - onset of deconfinement? - 1st order phase transition? - critical point?

Earlier experiments: at AGS, low-energy SPS: limited in observables, statistics

New : RHIC plans low energy runs

CBM – Physics CaseCBM – Physics Case

SIS 300 @ FAIR: ideal for 2nd generation experiment!

CBM: rare probes, high interaction ratescharm, dileptons, fluctuations, correlations


CBM collaborationCroatia: RBI, Zagreb

China:Wuhan Univ.Hefei Univ.

Cyprus: Nikosia Univ. Czech Republic:CAS, RezTechn. Univ. Prague

France: IReS Strasbourg

Hungaria:KFKI BudapestEötvös Univ. Budapest

India:VECC KolkataIOP Bhubaneswar*Univ. Chandighar*Univ. Varanasi*

Korea:Korea Univ. SeoulPusan National Univ.

Norway:Univ. Bergen

Germany: Univ. Heidelberg, Phys. Inst.Univ. HD, Kirchhoff Inst. Univ. FrankfurtUniv. KaiserslauternUniv. Mannheim Univ. MünsterFZ RossendorfGSI Darmstadt

Poland:Krakow Univ.Warsaw Univ.Silesia Univ. KatowiceNucl. Phys. Inst. Krakow* Portugal: LIP Coimbra

Romania: NIPNE Bucharest

Russia:IHEP ProtvinoINR TroitzkITEP MoscowKRI, St. PetersburgKurchatov Inst., MoscowLHE, JINR DubnaLPP, JINR DubnaLIT, JINR DubnaMEPHI MoscowObninsk State Univ.PNPI GatchinaSINP, Moscow State Univ. St. Petersburg Polytec. U.

Ukraine: Shevshenko Univ. , Kiev

* to be approved by CB

> 40 institutions

> 350 Members

open for new partners!


The CBM ExperimentThe CBM Experiment tracking, momentum, vertex reconstruction:

silicon pixel/strip detectors (STS) in magnetic dipole field

electron ID: RICH & TRD (& ECAL) suppression 104

hadron ID: TOF (& RICH)

photons, 0, ID: ECAL

event characterization (PSD)

high speed DAQ, only high-level triggers

not necessarily fixed layout!

more like „facility“


Alternative CBM setup: Alternative CBM setup: DimuonsDimuons Dimuon setup studied with

active muon absorbers (Fe + C + detector layers) after the Silicon Tracker

... move absorbers out for hadron runs.


Challenge: Au+Au collisions, 25 GeV/n:

high track densities:

600 charged particles in 25o

high r/o speed, radiation hardness: 10 MHz interaction rate (109 ions/s on 1% int target), only high-level triggers.

Tasks:

track reconstruction for particles with 0.1 GeV/c < p 10-12 GeV/c , momentum resolution ~ 1% at 1 GeV/c,large lateral coverage

primary and secondary vertex reconstruction (resolution 50 m)

V0 track pattern recognition (low-mass vector mesons lepton pairs, open charm decays, hyperons, e+e- pairs from -conversion)

D+ → ++K- (c = 317 m)

D0 → K-+ (c = 124 m)

Silicon Tracking and VertexingSilicon Tracking and Vertexing


Vertexing: "VTS"

2 (3) MAPS stations. z = (5), 10, 20 cm 150 µm Si In vacuum. No layout yet.

Tracking: "STS"

2 HYBRID Pixel stations: z = 30, 40 cm 750 µm Si No layout yet.

4 Micro-STRIPS stations: z = 50, 60, 75, 100 cm 400 µm Si Detailed station layout.Detailed station layout.

Conceptional Detector GeometryConceptional Detector Geometry

vacuum

2.5º

25ºVTSSTS

very very thin thin low-mass

low-mass


GEANT GEANT implementation:implementation:

•dipole magnet, dipole magnet,

1Tm bending power1Tm bending power

•VTS in vacuum VTS in vacuum sectionsection

•beam pipebeam pipe

•STS stationsSTS stations1 m1 m

Activities started on: optimization of layout,

robust tracking,

vertexing,

detector/system R&D


Microstrip Tracking StationsMicrostrip Tracking Stations

New concept:

r/o

double-sided sensors

50 µm strip pitch, 15 deg stereo angle

strip lengths 4-12 cm

r/o through thin, long analog cables !

r/o electronics

sensors

detector module

Sensor arrangement and hit digitization scheme.

Old concept:

"radial" arrangement of sectors


Microstrip Microstrip Stations:Stations:conceptional structure

r/o electronics

sensors

detector module

Station 6z = 60 cm

Station 5z = 50 cm

Station 7z = 75 cm

Station 8z = 100 cm


thin: standard: thick: thick-2: thick-3:

MAPS 2×150 µm 2×150 µm 2×150 µm 2× 150 µm 2× 150 µm Hybrid 2×200 µm 2×750 µm 2×800 µm 2×1000 µm 2×1600 µm Strips 4×200 µm 4×400 µm 4×800 µm 4×1000 µm 4×1600 µm

standard

thin

thickthick-2

thick-3

Momentum ResolutionMomentum Resolution

Thickness: effective,sensor + support/cables.

How much passive material (support, cables etc) will finally add up?

Readout: What sensor thickness for what S/N?

Detailed simulations being prepared.

Study impact on physics.


Track Reconstruction EfficiencyTrack Reconstruction Efficiency

primary tracks

97.02 ± 0.09

all reconstructed tracks

92.17 ± 0.14

Track finder: Cellular Automaton and Kalman Filter: - with 2 Hybrid Pixel + 4 Strip Stations,

- standard settings: include vertex,

hits in >3 consecutive stations.


primary tracks

94.88 ± 0.12

all reconstructed tracks

90.01 ± 0.15

Microstrip-Only Track ReconstructionMicrostrip-Only Track Reconstructionstandard detector configuration: L1 tracking with 2 Hybrid pixel + 4 Strip Stations

2 Strip Stations (avoid 2nd technology)

What's the design goal?

Important: Include robustness!


Tracking: double stations strips

Vertexing with 2 MAPS stations:

either: at 5 cm + 10 cm,

or: at 10 cm + 15 cm.

Tracking with four strip projections per station:Tracking with four strip projections per station:

Frontal viewFrontal viewxy+uvxy+uv Side viewSide viewxy uv

robust "space points"

Microstrip-only trackerMicrostrip-only tracker


Microstrip Double-StationsMicrostrip Double-Stations

4 hit projections on the strip planes

xy uv

0o3.75o

3.75o

-3.75o

-3.75o

11.25o-11.25o

Δz 1 cm


Tracking Stations: Tracking Stations: Layout Studies Layout Studies

Occupancies:

Up to 5% in hottest sectors of station 5 (central collisions).

Go down with radial distance from the beam axis, and with distance from the target ...... as expected.

The CA track finder yields tracking efficiencies ~97%.

Together with tracking study: powerful design tool.

Design criteria: - Save r/o channels in outer regions: Longer strips there! - Short strips close to beam line.


Microstrip Sensor DevelopmentMicrostrip Sensor DevelopmentTwo streams of activities:

double-sided, different technologies

1) In CBM Collaboration (R&D at MSU SiLab, Moscow)

300 µm, polysilicon biassing, p-stop

connectivity: top/bottom + sides

2) R&D at GSI, together with CIS, Germany

300 µm, punch-through biassing, p-spray, double-metal

connectivity: r/o at top/bottom edge

n side: "vertical" strips

p side: "stereo" strips

p side with "double metal"

blue: double metal connections of strips in regions I to III

n side: "vertical" strips

III

LY

LX

r/o direction

r/o directionI II


R&D with CIS Erfurt, Germany:R&D with CIS Erfurt, Germany: (http://www.cismst.de/english/frameset.html)

CBM: Opportunity to participate in reseach CBM: Opportunity to participate in reseach project of CIS (focus on rad hard detectors). project of CIS (focus on rad hard detectors).

CBM sensor prototypes as "test objects".

Sensor design: finished 10/2006.End 2006: batch of ~ 20+ wafers.End 2006: batch of ~ 20+ wafers.

Plenty of sensors for a variety of tests of r/o electronics and detector concept.

Set up Silicon labs at GSI + other institutes. Test beam + telescope at GSI.

256 x 256 strips80 µm pitch90 deg stereo angle256 x 256 strips

50 µm pitch90 deg stereo angle

1024 x 1024 strips50 µm pitch15 deg stereo angle

4" wafer, 280 µm thick

design finished

design finished

design partlyfinished


Microstrip Detector ReadoutMicrostrip Detector ReadoutTwo streams of activities:

1) In the CBM Collaboration (MEPhi/MSU, Moscow): R&D on fast self-triggered low-power electronics blocks

2) Exploration of the NXYTER chip in collaboration with the Consortium

DETectors for Neutron Imaging http://jra1.neutron-eu.net/jra1 dual polarity input pitch: 50.7 µm 128 channels per chip amplitude measurement data driven token-ring r/o architecture count rates: ~160 kHz/strip charge collection 30 ns peaking time small (~2 ns) timing jitter thresholds: > 2700 e dynamic range: different for +/- power: ~ 13 mW/channel (high!!!) produced in 0.35 m CMOS

Specs very similar to the CBM needs!1st chip submission in March 2006.

Aim: Test and modify this chip. Construction of a demonstrator microstrip detector module for CBM.

Close ties to the project through Head of GSI Detector Lab

GSI: significant participation in funding of chip submission (Summer 2006).


N-XYTER Submitted via CMP N-XYTER Submitted via CMP Dies Expected Sept. 25Dies Expected Sept. 25thth 2006 2006

128 analoginputs

poisson distributedat 32 MHz

total average

input rate

8 LVDSoutput lines

at 4 x 32MHz:time stamp, channel no.

+ 1 differential,

analog output

AMS CMOS 0.35µ with thick metal four


Study on Mechanical Structure Study on Mechanical Structure Elements (microstrip module): Elements (microstrip module):

module

sensor holders

flat cable routing

2-module structure, building block of detector stations

Study together with ITEP Moscow:

Based on ALICE ITS studies, and CBM STS layout concept.Carbon fibre.

"very preliminary,

brain-storming

designs"


Vertex Tracking SystemVertex Tracking System

Sensor Requirements: pitch 20 μm thickness below 100 μm single hit resolution : 3 μm radiation tolerant, design goal 1013 neq/cm2

ultimate read-out time 5-10 μs

Monolithic Active Pixel Sensors (MAPS)

R&D together with IPHC (IReS) Strasbourg development of fast column//architecture development of radiation tolerant sensors

(from some 1012 to 1013 neq /cm2)

longer lifetime of first MAPS station: enlarge distance from target: 5 cm → 10 cm

Hybrid pixels:

at least for now:

- too thick- too large pixels

- power dissipation requires cooling.

SOI pixels:

in a small process: interesting!

MAPS with depletion layer:

sounds interesting!


R&D goals with MAPS: R&D goals with MAPS: Radiation tolerance & readout speedRadiation tolerance & readout speed

R&D goals with MAPS:

radiation tolerance: ~1012 1013 1 MeV nequiv.

readout time: 10 sec, column parallel r/o

Expected situation in CBM:

Fluence at 1st MAPS station:

~10 1-MeV nequiv. per event

detector partly destroyed after 1012 reactions corresponds to 105 D mesons detected (already decent measurement!)

Possible running conditions:

a) 1 day detector lifetime at 107 reactions/s, 100 events piled up, or

b) 4 month detector lifetime at 105 reactions/s, no pile-up events.

URQMD, Au+Au 25 GeV/nucleon

Fluence of 1 MeV nequiv./cm2 in 1st MAPS station at z = 5cm

Kpn

What about retracting the 1st MAPS station from the target?


realistic tracking in magnetic field, 2 MAPS, 2 Hybrid pixel, 4 Strip stations proton identification required

Benchmark for SVT and STS Performance: Benchmark for SVT and STS Performance: DD00 mesons, Au+Au collisions at 25 AGeV mesons, Au+Au collisions at 25 AGeV

D0 production cross section from HSD 25 AGeV Au+Au from UrQMD

minimum bias collisions

1st MAPS station at z = 5 cm

D0

S/B = 3.5

1st MAPS station at z = 10 cm

dose × ¼

S/B × ¼

no gain!!


Summary - CBMSummary - CBMCBM is a baseline experiment at FAIR. Running from 2014/15.

CBM offers very interesting physics program on the QCD phase diagram.

Unique features expected in CBM energy range: First order phase transition, critical point

As a 2nd generation experiment, CBM will be able to study: rare probes, fluctuations and correlations!

Detector development under way

Increasingly realistic feasibility studies are performed

→ Technical Proposal in ~2007.


The Silicon Tracking and Vertex Detection System is the core of CBM.

Detector concept: Tracker (Microstrips) + Vertex Detector (MAPS)

R&D activities:

- layout optimization: Ongoing. New and powerful tools available for realistic detector/physics simulations.

- tracking studies: Ongoing- sensor development: Ongoing- r/o electronics development: Ongoing- mechanical studies: Beginning

Still may gaps to fill, including:

- realistic sensor shapes, support material in simulations. - realistic FLUKA radiation study. - R&D on module prototypes: Microstrips & MAPS. - thin sensors, low-mass r/o cables, low-mass support structures.

- ...

Summary – Silicon DetectorsSummary – Silicon Detectors


Data-Push Architecture, Data Flow

Each detector channel detects autonomously all hits FEE design.

An absolute time stamp, precise to a fraction of the sampling period, is associated with each hit.

All hits are shipped to the next layer (usually data concentrators).

Association of hits with events done later using time correlation.

Typical parameters:

(few % occupancy, 107 interaction rate)

some 100 kHz hit rate per channel

few MByte/sec per channel

whole CBM detector: ~ 1 Tbyte/sec

Documents

1 J.M. Heuser CBM Silicon Tracking and Vertex Detection System Development of a Silicon Tracking and Vertex Detection System for the CBM Experiment at