Electron pair analysis for high multiplicity events in nucleus-nucleus collisions
Nucleus-nucleus collisions at the future facility in Darmstadt -
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Nucleus-nucleus collisions at the future facility in Darmstadt -
Compressed Baryonic Matter at GSI
Outline:
Dense baryonic matter: fundamental physics Experimental observables Technical challenges and (possible) solutions
Peter Senger
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States of strongly interacting matter
baryons hadrons partons
Compression + heating = quark-gluon plasma (pion production)
Neutron stars Early universe
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Exploring the phase diagram of strongly interacting matter
CERN-SPS, RHIC, LHC: high temperature, low baryon density
GSI (SIS300): moderate temperature, high baryon density
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B 3-80 , T 130 MeV
Fundamental questions:
Equation-of-state at high densities: stability of neutron stars, supernova dynamics
deconfinement
In-medium hadron properties: chiral symmetry restoration, origin of hadron masses?
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Creating high baryon densities in the laboratoryby heavy-ion collisions
Transport calculationsB. Friman, W. Nörenberg, V.D. Toneev Eur. Phys. J. A3 (1998) 165
SIS300
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Pion multiplicities per participating nucleons
SIS100/300
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Statistical hadron gas modelP. Braun-Munzinger et al.
Nucl. Phys. A 697 (2002) 902
Experimental situation : Strangeness enhancement ?Experimental situation : Strangeness production
in central Au+Au and Pb+Pb collisions
New results from NA49 (CERN Courier Oct. 2003)
SIS100300
SIS100300
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Comparison of experimental data to results of transport codes E.L. Bratkovskaya, W. Cassing, M. van Leeuwen, S. Soff, H. Stöcker, nucl-th/0307098
“Flow generated by extra pressure generated by partonic interactions in the early phase of a central Au+Au/Pb+Pb collision”
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Mapping the QCD phase diagram with heavy-ion collisions
B 6 0
B 0.3 0
baryon density: B 4 ( mT/2)3/2 x
[exp((B-m)/T) - exp((-B-m)/T)] baryons - antibaryons
Analysis of particle ratios with statistical model: chemical freeze-out
P. Braun-Munzinger
SIS300
gasliquid
coexistence
C. R. Allton et al, hep-lat 0305007
Lattice QCD : maximal baryon number density fluctuations at TC for q = TC (B 500 MeV)
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CBM physics topics and observables
1. In-medium modifications of hadrons onset of chiral symmetry restoration at high B
measure: , , e+e- open charm (D mesons) 2. Strangeness in matter (strange matter?) enhanced strangeness production ?
measure: K, , , , 3. Indications for deconfinement at high B anomalous charmonium suppression ?
measure: J/, D
softening of EOS
measure flow excitation function 4. Critical point event-by-event fluctuations 5. Color superconductivity precursor effects ??
Note: In heavy ion collisions
(, , ) e+e- not measured from 2 – 40 AGeV
J/ not measured below 158 AGeV
D mesons not measured at all
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pn
++
K
e+
e-
p
Looking into the fireball …
… using penetrating probes:
short-lived vector mesons decaying into electron-positron pairs
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Measure spectral functions of vector mesons via their decay into electron-positron pairs (penetrating probes!)using Ring Imaging Cherenkov detectors
NA45/CERES @ CERN-SPS
CH4 radiator gas: thr= 32
HADES @ GSI
C4F10 radiator gas: thr= 18.3UV-det.: fast CsI cathode
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Invariant mass of electron-positron pairs from Pb+Au at 40 AGeVCERES Collaboration S. Damjanovic and K. Filimonov, nucl-ex/0109017
≈185 pairs!
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Signatures of the quark-pluon plasma ?
Anomalous suppression of charmonium (J/) ???
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central collisions 25 AGeV Au+Au 158 AGeV Pb+Pb
J/ multiplicity 1.5·10-5 1·10-3 beam intensity 2·108/s 2·107/sinteractions 8·106/s (4%) 2·106/s (10%)central collisions 8·105/s 2·105/sJ/ rate 12/s 200/s 6% J/e+e- (+-) 0.7/s 12/sspill fraction 0.8 0.25 acceptance 0.25 0.1J/ measured 0.14/s 0.3/s 8·104/week 1.8·105/week
J/ experiments: a count rate estimate10 50 120 210 Elab [GeV]
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Charmed mesons
Some hadronic decay modes
D (c = 317 m):D+ K0+ (2.90.26%)
D+ K-++ (9 0.6%)
D0 (c = 124.4 m):D0 K-+ (3.9 0.09%)
D0 K-+ + - (7.6 0.4%)
experimental challenges:low production cross sectionlarge combinatorial backgroundmeasure displaced vertex with resolution of 30m
D meson production in pN collisions
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SIS18 SIS100/
300
Meson production in central Au+Au collisionsW. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745
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Observables:p, , K, , , , , , , , D, J/(3-diff. cross sect., correlations, dileptonic decays)exotica: strange clusters, pentaquarks, …
The experimental program of CBM:
Collision systems:A+A collisions from 8 to 45 (35) AGeV, Z/A=0.5 (0.4) p+A collisions from 8 to 90 GeVp+p collisions from 8 to 90 GeVBeam energies up to 8 AGeV: HADESAccelerator:SIS300High beam intensity and duty cycle,Excellent beam quality, no halo !Available for several month per year
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Experimental challenges
107 Au+Au 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
Central Au+Au collision at 25 AGeV:URQMD + GEANT4
160 p 400 -
400 + 44 K+ 13 K-
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The CBM Experiment
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, π, η, and muons: electromagn. calorimeter (ECAL)
High speed data acquisition and trigger system
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CBM in GEANT4
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CBM R&D working packages Feasibility, Simulations
D Kπ(π)GSI Darmstadt, Czech Acad. Sci., RezTechn. Univ. Prague
,ω, e+e-
Univ. KrakowJINR-LHE Dubna
J/ψ e+e-
INR Moscow
Hadron ID Heidelberg Univ,Warsaw Univ.Kiev Univ. NIPNE BucharestINR Moscow
GEANT4: GSI
TrackingKIP Univ. HeidelbergUniv. MannheimJINR-LHE Dubna
Design & constructionof detectors
Silicon PixelIReS StrasbourgFrankfurt Univ.,GSI Darmstadt,RBI Zagreb,Krakow Univ. LBNL Berkeley
Silicon StripSINP Moscow State U.CKBM St. PetersburgKRI St. Petersburg
RPC-TOFLIP Coimbra, Univ. Santiago de Com.,Univ. Heidelberg,GSI Darmstadt,NIPNE BucharestINR MoscowFZ RossendorfIHEP ProtvinoITEP Moscow
Fast TRDJINR-LHE, DubnaGSI Darmstadt,Univ. MünsterINFN Frascati
Straw tubesJINR-LPP, DubnaPNPI GatchinaFZ RossendorfFZ Jülich
ECAL ITEP Moscow GSI Darmstadt
RICH IHEP Protvino GSI Darmstadt
Trigger, DAQKIP Univ. HeidelbergUniv. MannheimGSI DarmstadtJINR-LIT, DubnaKFKI BudapestSilesia Univ.
MagnetJINR-LHE, DubnaGSI Darmstadt
AnalysisGSI Darmstadt,Heidelberg Univ,
Data Acquis.,Analysis
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EU FP6 Hadron Physics (2004 – 2006)
Joint Research Projects (approved):
• Fast gaseous detectors • Advanced TOF Systems• Future DAQ and trigger systems
Network activities (approved):
• CBMnet
CBM Participation in EU Programmes:
INTAS-GSI (2004-2005)
approved projects:
• Transition Radiation Detectors JINR LHE Dubna, NC PHEP Minsk, INFN Frascati, GSI Darmstadt • Straw tube tracker: JINR LPP Dubna, LPI Moscow, PNPI Gatchina, TU Warsaw, FZ Rossendorf, FZ Jülich
• Resistive Plate Chambers INR Troitzk, IHEP Protvino, ITEP Moscow, LIP Coimbra, Univ. Heidelberg
• Electromagnetic calorimeter ITEP Moscow, Polimersintez Wladimir, Univ. Krakow, GSI Darmstadt
New call EU FP6 (opened Nov.03, closed Mar04):
• Design of new facilities • Construction of new facilities
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CBM R&D Collaboration : 38 institutions , 15 countriesCroatia:
RBI, Zagreb
Cyprus: Nikosia Univ. Czech Republic:Czech Acad. Science, RezTechn. Univ. Prague France: IReS Strasbourg
Germany: Univ. Heidelberg, Phys. Inst.Univ. HD, Kirchhoff Inst. Univ. FrankfurtUniv. Mannheim Univ. MarburgUniv. MünsterFZ RossendorfGSI Darmstadt
Russia:CKBM, St. PetersburgIHEP ProtvinoINR TroitzkITEP MoscowKRI, St. PetersburgKurchatov Inst., MoscowLHE, JINR DubnaLPP, JINR DubnaLIT, JINR DubnaPNPI GatchinaSINP, Moscow State Univ.
Spain: Santiago de Compostela Univ. Ukraine: Shevshenko Univ. , Kiev
USA: LBNL Berkeley
Hungaria:KFKI BudapestEötvös Univ. Budapest
Italy: INFN CataniaINFN Frascati
Korea:Korea Univ. SeoulPusan Univ.
Poland:Krakow Univ.Warsaw Univ.Silesia Univ. Katowice Portugal: LIP Coimbra
Romania: NIPNE Bucharest