CBM – Technical Challenges
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Transcript of 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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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N-XYTER ArchitectureN-XYTER Architecture
S. Buzzetti, Uni Heidelberg
DETNI Coll.
Front-end targeted forSilicon strip (pos & neg)GEM's and MSGC's
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Fast Gas Tracking DetectorsFast Gas Tracking Detectors
MUCH detectorμ+-μ- setup doing
hadronic observables
e+-e- setup
Needed in many places
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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
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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
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RPC DevelopmentRPC Development
P. Fonte, LIP, Coimbra
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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
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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
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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
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The EndThe End
Thanks for your attention
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The EndThe End
Spares
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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
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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
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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