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The CBM Experiment at FAIR
Peter Senger Moscow Nov.
2004

• Outline
• ? Mapping the QCD phase diagram
• ? A universal second generation
  experiment
• Requirements, technical challenges,
  performance

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The future Facility for Antiproton an Ion
Research (FAIR)
SIS 100 Tm SIS 300 Tm U 35 AGeV p 90 GeV
Cooled antiproton beam Hadron Spectroscopy
Ion and Laser Induced Plasmas High Energy
Density in Matter
Structure of Nuclei far from Stability
Compressed Baryonic Matter
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States of strongly interacting matter
baryons hadrons partons

Compression heating quark-gluon
plasma (pion production)
Strangeness" of dense matter ? In-medium
properties of hadrons ? Compressibility of
nuclear matter? Deconfinement at high baryon
densities ?
Neutron stars
Early universe
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Mapping the QCD phase diagram with heavy-ion
collisions
Lattice QCD calculations Fedor Katz, Ejiri et
al.
SIS300
net baryon density ?B ? 4 ( mT/2?h2c2)3/2 x
exp((?B-m)/T) - exp((-?B-m)/T) baryons
- antibaryons
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Trajectories (3 fluid hydro)
Ivanov Toneev
Hadron gas EOS
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(No Transcript)
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Diagnostic probes UU 23 AGeV
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CBM physics topics and observables
? In-medium modifications of hadrons ?
onset of chiral symmetry restoration at high ?B
measure ?, ?, ? ? ee-
open charm (D mesons)
? Strangeness in matter (strange matter?)
? enhanced strangeness production ?
measure K, ?, ?, ?, ?
? Indications for deconfinement at high ?B
? anomalous charmonium suppression ?
measure J/?, D
? Critical point ? event-by-event
fluctuations
? Color superconductivity ?
precursor effects ?
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But perhaps the most interesting and surprising
thing about QCD at high density is that, by
thinking about it, one discovers a fruitful new
perspective on the traditional problem of
confinement and chiral-symmetry breaking.
Frank Wilczek, Physics Today, Aug.2000
(Nobel prize 2004 )

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Strangeness production in central AuAu and
PbPb collisionsAGS SPS RHIC

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J/? experiments a count rate estimate
central collisions 25 AGeV AuAu 158 AGeV
PbPb J/?? multiplicity
1.510-5 110-3 beam
intensity 1109/s
2107/s interactions
1107/s (1) 2106/s (10) central
collisions 1106/s
2105/s J/? rate
15/s 200/s 6
J/???ee- (??-) 0.9/s
12/s spill fraction
0.8 0.25
acceptance 0.25
? 0.1 J/? measured
0.17/s ? 0.3/s
? 1105/week
? 1.8105/week
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Open charm
D meson production in pN collisions
Some hadronic decay modes D? (c? 317 ?m) D ?
K0? (2.9?0.26) D ? K-?? (9 ? 0.6) D0 (c?
124.4 ?m) D0 ? K-? (3.9 ? 0.09) D0 ? K-?
? ?- (7.6 ? 0.4)
Measure displaced vertex with resolution of ?
30 µm !
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Meson production in central AuAu collisions
W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl.
Phys. A 691 (2001) 745
SIS100/ 300
SIS18
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Experimental challenges
Central AuAu collision at 25 AGeV URQMD
GEANT4 160 p 400 ?- 400 ? 44 K
13 K-

• ? 107 AuAu reactions/sec
• (beam intensities up to 109 ions/sec, 1
  interaction target)
• ? determination of (displaced) vertices with high
  resolution (? 30 ?m)
• ? identification of electrons and hadrons

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Feasibility studies
Event generators URQMD, PLUTO Transport
GEANT3,4 via VMC
? Radiation hard Silicon pixel/strip detectors in
a magnetic dipole field ? Electron detectors
RICH TRD ECAL pion suppression up to 105 ?
Hadron identification RPC, RICH ? Measurement
of photons, p0, ?, and muons electromagn.
calorimeter (ECAL)
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Acceptance
pt (GeV/c)
rapidity
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Low mass electron-positron pairs
Assumptions ideal tracking and electron
identification Background URQMD AuAu 25 AGeV
GEANT4

• Cuts
• 1. single electron
• pt gt 0.1 GeV/c
• d lt 50 mm
• 2. electron pair
• vz lt 0.1 cm
• vt lt 0.01 cm
• D lt 0.01 cm
• T gt 10

S/B 0.3 (??) S/B 1.2 (?)
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Pion misidentification
a)0
b)0.01
c)0.1
d)1
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Feasibility studies charmonium measurements
Assumptions ideal tracking, ideal electron
identification, Pion
suppression 104 Background Au Au UrQMD
GEANT4 Cut pT gt 1 GeV/c

J/?
15 AGeV
J/?
25 AGeV
J/?
35 AGeV
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Status feasibility studies

• Tools simulation framework, VMC, UrQMD,
  GEANT3/4
• Dilepton decays of vector mesons (?, ?, f, J/?)
• background physical electron sources,
  secondary electrons, misidentified p
• study of J/? identification via muon decay in
  progress
• no track and momentum reconstruction
• no electron (muon) ID
• high statistics background simulation needed for
  J/? study
• Hadronic decays of D-mesons and (multistrange)
  hyperons
• background UrQMD (incl hyperons)
• track reconstruction without magnetic field,
• no track and momentum reconstruction in magnetic
  field,
• no hadron identification
• high statistics background simulation needed for
  D meson study
• upper limit for secondary vertex resolution
  (depending on thickness
• of Silicon detector)
• Event-by-event fluctuations

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Experimental conditions
Hit rates for 107 minimum bias AuAu collisions
at 25 AGeV
Rates of gt 10 kHz/cm2 in large part of detectors
! ? main thrust of our detector design studies
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Design of a Silicon Pixel detector
Silicon Tracking System 3 Pixel Stations/ 4
Strip Stations Vertex tracking by two first pixel
layers at 5 cm and 10 cm downstream target

• Design goals
• low materal budget d lt 200 µm
• single hit resolution lt 20 µm
• radiation hard (dose 1015 neq/cm2)
• fast read out

• Roadmap
• RD on Monolithic Active Pixel Sensors (MAPS)
• pitch 20 µm
• thickness below 100 µm
• single hit resolution ? 3 µm
• Problem radiation hardness and readout speed
• Fallback solution
• next generation of thin Hybrid detectors

MIMOSA IV IReS / LEPSI Strasbourg
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Silicon Strip Tracker
4 Strip tracking stations
Tracking Station Nr. 4
Double sided Si-Strip detectors thickness 100 µm
pitch 25 µm Stereo angle 15o
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Design of a fast RICH

• Design goals
• electron ID for ? gt 42
• e/p discrimination gt 100
• hadron blind up to about 6 GeV/c
• low mass mirrors (Be-glass)
• fast UV detector

URQMD GEANT4 AuAu 25 AGeV radiator (40 He
60 CH4) ? 40 rings per event, 30-40 photons per
ring (incl. efficiencies)
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Design of a fast TRD

• Design goals
• e/p discrimination of gt 100 (p gt 1 GeV/c)
• High rate capability up to 150 kHz/cm2
• Position resolution of about 200 µm
• Large area (? 500 m2, 9 layers)

Simulation of pion suppression TRD with fast
gaseous detector

• Roadmap
• Outer part ALICE TRD
• Inner part
• MWPC/GEM/micromegas
• Straw tube TRT (ATLAS)
• Fast read-out electronics

Successful tests of prototypes (MWPC, GEM) in
July 2004 at SIS/GSI
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RD on a high rate RPC

• Design goals
• Time resolution 80 ps
• High rate capability up to 25 kHz/cm2
• Efficiency gt 95
• Large area ? 150 m2
• Long term stability

Prototype test
detector with plastic electrodes (resistivity
109 Ohm cm.) P. Fonte, Coimbra
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Status detector simulations

• CBM global detector layout and arrangement
• based on educated guess
• no global track matching
• required detector granularity and hit
  resolution (in progress)
• Silicon tracker
• MAPS digitizer studies in progress
• Strips layout design in progress
• RICH
• simulations of Cherenkov photon production,
  absorption, reflection and
• detection using GEANT (incl. radiator, mirror,
  photon detector)
• background studies (UrQMD, GEANT)
• ring recognition
• matching of rings and tracks
• TRD
• simulations of electron and pion efficiencies
• (optimization of radiator, gas detector,
  number of detector layers)
• granularity, hit resolution, digitizer
• RPC
• simulations on layout, granularity, hit
  resolution, digitizer

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Status detector RD

• Silicon tracker
• MAPS radiation hardness, read-out speed
• Strips waiting for Layout
• RICH
• design of mirror
• design of photomultipliers for photon detector
  (quantum efficiency, costs)
• TRD
• fast gas detector tests performed successfully
• RPC
• test measurements on rate capability, time
  resolution, noise
• glass research, temperature effects,
• performance of large area detector modules ?
• ECAL
• test measurements of shashlik modules
• reduction of Moliere radius ?
• Dipole magnet
• 2 field configurations used for tracking
• delta-electron studies in progress (additional
  suppression required)

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Status trigger, DAQ, FEE

• Trigger
• charmonium high pt electron-positron pair
  (under investigation)
• D meson fast tracking algorithm, trigger on
  displaced vertex
• low-mass vector meson ???
• hyperons no trigger (event rate 25 kHz)
• DAQ
• self triggered frontends
• system architecture under development
• FEE
• First meeting of ASIC desing working group on
  Sept. 25, 2004

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Experimental program of CBM
Observables Penetrating probes ?, ?, ?, J/?
(vector mesons) Strangeness K, ?, ?, ?, ?,
Open charm Do, D? Hadrons ( p, p), exotica
Detector requirements Large geometrical
acceptance good hadron and electron
identification excellent vertex resolution high
rate capability of detectors, FEE and DAQ
Systematic investigations AA collisions from 8
to 45 (35) AGeV, Z/A0.5 (0.4) pA collisions
from 8 to 90 GeV pp collisions from 8 to 90
GeV Beam energies up to 8 AGeV HADES
? ? ee- ?
Large integrated luminosity High beam intensity
and duty cycle, Available for several month per
year
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CBM RD working packages
FEE, Trigger, DAQ
Feasibility studies Simulations
Design construction of detectors
?,?, ? ?ee- Univ. Krakow JINR-LHE Dubna
Framework GSI
Silicon Pixel IReS Strasbourg Frankfurt
Univ., GSI Darmstadt, RBI Zagreb, Univ. Krakow
Fast TRD JINR-LHE, Dubna GSI Darmstadt, Univ.
Münster NIPNE Bucharest
KIP Univ. Heidelberg Univ. Mannheim GSI
Darmstadt JINR-LIT, Dubna Univ. Bergen KFKI
Budapest Silesia Univ. Katowice Warsaw Univ.
Tracking KIP Univ. Heidelberg Univ.
Mannheim JINR-LHE Dubna JINR-LIT Dubna
J/? ? ee- INR Moscow GSI
Straw tubes JINR-LPP, Dubna FZ Rossendorf FZ
Jülich Tech. Univ. Warsaw
Silicon Strip Moscow State Univ CKBM St.
Petersburg KRI St. Petersburg Univ. Obninsk
J/? ? µµ- PNPi St. Petersburg SPU St. Petersburg
Ring finder JINR-LIT, Dubna
ECAL ITEP Moscow Univ. Krakow
RPC-TOF LIP Coimbra, Univ. Santiago Univ.
Heidelberg, GSI Darmstadt, Warsaw Univ. NIPNE
Bucharest INR Moscow FZ Rossendorf IHEP
Protvino ITEP Moscow RBI Zagreb Univ. Marburg
p, K, p ID Heidelberg Univ, Warsaw Univ. Kiev
Univ. NIPNE Bucharest INR Moscow
D ? Kp(p) GSI Darmstadt, Czech Acad. Sci.,
Rez Techn. Univ. Prague
RICH IHEP Protvino GSI Darmstadt
?, ?,O PNPi St. Petersburg SPU St. Petersburg
Magnet JINR-LHE, Dubna GSI Darmstadt
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CBM Collaboration 39 institutions, 14 countries
Croatia RBI, Zagreb Cyprus Nikosia Univ.
  Czech Republic Czech Acad. Science,
Rez Techn. Univ. Prague   France IReS
Strasbourg Germany Univ. Heidelberg, Phys.
Inst. Univ. HD, Kirchhoff Inst. Univ.
Frankfurt Univ. Mannheim Univ. Marburg Univ.
Münster FZ Rossendorf GSI Darmstadt    
Russia CKBM, St. Petersburg IHEP Protvino INR
Troitzk ITEP Moscow KRI, St. Petersburg Kurchatov
Inst., Moscow LHE, JINR Dubna LPP, JINR
Dubna LIT, JINR Dubna Obninsk State Univ. PNPI
Gatchina SINP, Moscow State Univ. St. Petersburg
Polytec. U. Spain Santiago de Compostela Univ.
  Ukraine Shevshenko Univ. , Kiev Univ. of
Kharkov
Hungaria KFKI Budapest Eötvös Univ.
Budapest Korea Korea Univ. Seoul Pusan National
Univ. Norway Univ. Bergen Poland Krakow
Univ. Warsaw Univ. Silesia Univ.
Katowice   Portugal LIP Coimbra Romania NIPNE
Bucharest
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Recent Financing Plan of the BMBF (13.9.04)