CBM – Technical Challenges

CBM – Technical CBM – Technical ChallengesChallenges

Walter F.J. Müller, GSI, Darmstadtfor the CBM Collaboration

23 November 2006 CCNU Wuhan, November 2006 2

Observables Observables →→ Detector Detector RequirementsRequirements

event-by-event fluctuationsflow excitation functionstrangeness production: K,

open charm: D0, D±,Ds

low-mass vector mesons: ρ,ω, hidden charm: J/Ψ

Momentum measurementHadron IDLepton ID: e or μPhoton detectionVertex reconstruction

High track density → highly granular detectorsLarge integrated luminosity high interaction rates (10 MHz) → fast detectors (100 kHz/ch) → efficient event selection several month/year beam → radiation hard detectors

Observables

Capabilities

Capacities


CBM SetupCBM Setup

Momentum measurementHadron IDLepton ID: e or μPhoton detectionVertex reconstruction

High track density → highly granular detectorsLarge integrated luminosity high interaction rates (10 MHz) → fast detectors (100 kHz/ch) → efficient event selection several month/year beam → radiation hard detectors

Capabilities

Capacities


Driving Factor 1: Rare ProbesDriving Factor 1: Rare Probes[W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745]

SIS100/ 300

J/Ψ → 107 int/sec

D → 106 int/sec

Integrated Luminosity:~ 1014 int/lifetime

for some sub-systems


High MultiplicityHigh Multiplicity

Central Au+Au collision at 25 AGeV:URQMD + GEANT

160 p 170 n360 - 330 + 360 0 41 K+ 13 K- 42 K0


Driving Factor 2: Hit DensitiesDriving Factor 2: Hit Densities

at Vertex Detector at end of STS at ToF Wall

up to 1 hit/mm2/evt up to 1 hit/cm2/evt 10-2 hit/cm2/evt

For Au + Au @ 25 A GeV central collisions:

x 1014 int/life→ ~ 2.5 MRad

replace Vertex Detectorafter one run

~ 25 KHz/cm2/sec

horz. planevert. plane


CBM Event Selection CBM Event Selection RequirementsRequirements In-medium modifications of hadrons

onset of chiral symmetry restoration at high ρB

measure: , , e+e- or μ+μ -

open charm (D0, D±) Strangeness in matter

enhanced strangeness production measure: K, , , ,

Indications for deconfinement at high ρB

anomalous charmonium suppression ? measure: D0, D± -

J/ e+e or μ+μ -

Critical point event-by-event fluctuations

measure: π, K

offline

assume archive rate:few GB/sec20 kevents/sec

offline

offline

trigger

trigger

trigger trigger on high pt e+e- or μ+μ- pair

trigger ondisplaced vertex

drives FEE/DAQarchitecture


Driving Factor 3: Tracking Driving Factor 3: Tracking TriggerTrigger Example: D0 K-+ (3.9%; c = 124.4 m)

reconstruct tracks find primary vertex find displaced tracks find secondary vertex

target

first two planesof vertex detector

few 100 μm

5 cm

high selectivity because combinatorics is reduced


DAQ – Event SelectionDAQ – Event Selection

Challenge: no conventional first level trigger first decision level requires tracking and vertexing

hard to do in a limited decision time straight forward to use farming to achieve throughput

Solution: build a system that is throughput limited, not latency

limited use self-triggered front-ends


L1 Select Some Programmable Logicand mostly CPU's

Highbandwidth

DAQ – Data Push ArchitectureDAQ – Data Push ArchitectureDetector

Cave

Shack

FEE

DAQ

Archive

time distribution

L2 Select

Self-triggered front-end

Autonomous hit detection

No dedicated trigger connectivity

All detectors can contribute to L1

Large buffer depth available

System is throughput-limitedand not latency-limited

Use term: Event Selection

Buffer


Front-End for Data Push Front-End for Data Push ArchitectureArchitecture Each channel detects autonomously all hits 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

concentrators) Association of hits with events done later using time

correlation

Typical Parameters: with few 1% occupancy and 107 interaction rate:

some 100 kHz channel hit rate few MByte/sec per channel whole CBM detector: 1 Tbyte/sec


Vertex DetectorVertex Detector

Challenge: ~30 x 30 μm pixel size cope with 1 Mhz interaction rate stand at least 1012 interactions low material budget (0.2-0.3 % X0)

Solutions: Active pixel sensors (MAPS) DEPFET sensors


Vertex Detector – MAPS Vertex Detector – MAPS DevelopmentDevelopment Base technology like STAR

Heavy Flavor Tracker (HFT)

Working on: faster readout:

column-parallel read-out short columns 10 MHz pixel rate @

1 mW/column radiation hardness

1 MRad and 2x1012 neq/cm2 demonstrated so far

low mass support structure

11 stst Draft Draft

M. Winter, IPHC, StrasbourgJ. Stroth, Uni. Frankfurt


Silicon Tracker Silicon Tracker

Challenges: Sensor

radiation hard (must stand 1014 interactions) 50 μm pitch, double sided, ~150 stereo, ladderable

Read-out self-triggered, 128 ch, radiation tolerant

Support Structure low mass likely need cooled sensors


Silicon Tracker – FEE Silicon Tracker – FEE DevelopmentDevelopment Start with N-XYTER chip from DETNI Collaboration

128 channels, self-triggered (designed for neutron detectors !)

2 ns time stamp accuracy 32 Mhit/sec readout bandwidth will be used in 2007/2008 prototyping

Next steps lower power; fully digital interface radiation hardness

Strategy use same architecture also for read-out of highly granular

gas detectors (e.g. GEM) → variants with adapted preamps


N-XYTER ArchitectureN-XYTER Architecture

S. Buzzetti, Uni Heidelberg

DETNI Coll.

Front-end targeted forSilicon strip (pos & neg)GEM's and MSGC's


Fast Gas Tracking DetectorsFast Gas Tracking Detectors

MUCH detectorμ+-μ- setup doing

hadronic observables

e+-e- setup

Needed in many places


Fast Gas Tracking Detectors Fast Gas Tracking Detectors

Challenges: hit density: 10-2 up to 1 hit/cm2

hit rate: 25 kHz up to 2.5 MHz/cm2

fluence: 1012 up to 1014 part/cm2 (~ 1 C/cm2)

Solution: up to a few 100 kHz/cm2: (TRD or intermediate Tracker)

high-rate MWPC'sseveral 100 m2 needed for TRD or intermediate trackersignificant R&D done in the last years

above a few 100 kHz/cm2: (parts of Muon system) GEM, Mircomegas

requirements depending on detailed MUCH layoutwork just starting within CBM


Time-of-Flight WallTime-of-Flight Wall

Challenges: Size: 150 m2

hit density: 10-2 hit/cm2

hit rate: 25 kHz/cm2

System time resolution <= 80 ps

Solution: Multigap RPC Counters with 'low' resistivity electrodes


RPC DevelopmentRPC Development

P. Fonte, LIP, Coimbra

0

20

40

60

80

100

120

140

160

180

200

0 10 20 30 40 50 60 70 80Counting Rate (kHz cm-2)

Sigma 2700 2725 2750

2775 2800 2850 3000For pairs expect ~60 ps

for MIPS

Example: Ceramic electrodes controlled resistivity alumina

109 Ω cm at room temperature efficiency drop

9% /100 kHz in single gap 2% @ 200 kHz for 4 gaps

Also under investigation: warm glass semiconductive glass

Outlook: 25 kHz/cm2 rate is achievable challenge is to control ageing

Single gap


SummarySummary

Hit rates and densities seem feasible

Main challenge is control radiation damage / ageing

→ long-term and comprehensive testing system integration

→ build complete sub-system prototypes


CBM collaborationCBM collaborationCroatia: RBI, Zagreb

China:CCNU, WuhanUSTC, Hefei

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

France: IReS Strasbourg

Hungaria:KFKI BudapestEötvös Univ. Budapest

India:VECC KolkataIOP BhubaneswarUniv. Chandighar

India (cont):Univ. VaranasiIIT Kharagpur

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


The EndThe End

Thanks for your attention


The EndThe End

Spares


Conventional FEE-DAQ-Trigger Conventional FEE-DAQ-Trigger LayoutLayout Detector

Cave

Shack

FEE

Buffer

L2 Trigger

DAQ

fbunch

Archive

Limitedcapacity

LimitedL1 triggerlatency

L1 TriggerL1

Acc

ept

Trigger

Primitives

Especially instrumented

detectors

Dedicatedconnections

Specializedtrigger

hardware

Modestbandwidth

Standardhardware


Fast Gas Detector DevelopmentFast Gas Detector Development MWPC Example: Double-

sided pad plane HCRTRD chamber for TRD

3mm max. drift; 12 mm Xe stable up to 200 kHz/cm2

π rejection of >100 can be achieved with 6 layers and foil radiator

M. Petrovici, NIPNE, Bucharest


Straw Detector with Segmented Straw Detector with Segmented AnodeAnode

Anode Anode segment 1segment 1

Anode segment 2Anode segment 2Anode segment 3Anode segment 3

11 22 33 44

V Peshekhonov, JINR, Dubna

Glass joint with 2 anode wiresand a read-out wire

Joint plus spacer unitFeed-Through

CBM – Technical Challenges

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