The CBM experiment - exploring the QCD phase diagram at high net baryon densities - Claudia Höhne, GSI Darmstadt CBM collaboration The CBM experiment • physics case, observables • detector layout • feasibility studies and R&D of detector components
Dec 31, 2015
The CBM experiment- exploring the QCD phase diagram at high net baryon densities -
Claudia Höhne, GSI Darmstadt
CBM collaboration
The CBM experiment
• physics case, observables
• detector layout
• feasibility studies and R&D of detector components
2 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
Physics caseCompressed Baryonic Matter @ FAIR – high B, moderate T:
searching for the landmarks of the QCD phase diagram• first order deconfinement phase transition • chiral phase transition• QCD critical endpoint
in A+A collisions from 10-45 AGeV starting in 2015
• physics program complementary to ALICE
• measurement of charm production at threshold A.
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3 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
High density matter
• high baryon and energy densities created in central Au+Au collisions
• remarkable agreement between different models
• max. net baryon densities from 5 - 40 AGeV ~ 1 - 2 fm-3 ~ (6 – 12) 0
(net baryon density = 1 fm-3 ~60)
• max. excitation energy densities from 5 - 40 AGeV ~ (0.8 – 6) GeV/fm3
(* = – mN, total energy density)
net baryon density excitation energy density
[CBM physics group, J. Randrup priv. com.]
4 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
Physics topics and Observables
Onset of chiral symmetry restoration at high B
• in-medium modifications of hadrons (,, e+e-(μ+μ-), D)
Deconfinement phase transition at high B • excitation function and flow of strangeness (K, , , , )• excitation function and flow of charm (J/ψ, ψ', D0, D, c)• sequential melting of J/ψ and ψ', charmonium suppression
The equation-of-state at high B
• collective flow of hadrons• particle production at threshold energies (open charm)
QCD critical endpoint• excitation function of event-by-event fluctuations (K/π,...)
• mostly new measurements• CBM Physics Book (theory) in preparation
5 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
The CBM experiment• tracking, momentum determination, vertex reconstruction: radiation hard silicon pixel/strip detectors (STS) in a magnetic dipole field
• hadron ID: TOF (& RICH)• photons, 0, : ECAL
• electron ID: RICH & TRD suppression 104
• PSD for event characterization• high speed DAQ and trigger → rare probes!
• muon ID: absorber + detector layer sandwich move out absorbers for hadron runs
MVD + STS
aim: optimize setup to include both, electron and muon ID (not necessarily simultaneously)
6 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
CbmRoot simulation framework• detector simulation (GEANT3)
• full event reconstruction: track reconstruction, add RICH, TRD and TOF info
• result from feasibility studies in the following: central Au+Au collisions at 25 AGeV beam energy
7 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
STS tracking
Challenge: high track density 600 charged particles in 25o
Task
• track reconstruction:
0.1 GeV/c < p 10-12 GeV/c
p/p ~ 1% (p=1 GeV/c)
• primary and secondary vertex reconstruction (resolution 50 m)
• V0 track pattern recognition
D+ → ++K- (c = 317 m)
D0 → K-+ (c = 124 m)
silicon pixel
and strip detectors
8 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
Open charm production• D0 → K-+ (c= 124 m)
• <D0> = 4∙ 10-5
• first MAPS detector at 10cm
• ~53 m secondary vertex resolution
• proton identification with TOF
1.6 107 central Au+Au collisions, 25 AGeV
central Au+Au, 25 AGeV
9 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
4"280 µm
Microstrip Sensors Tracking Stations
layout studies
module design
J. Heuser HK 22.2
Silicon Strip Sensor R&D
10 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
Fast self-triggered readout electronics
NXYTER chip produced; DETNI − GSI
test system under construction
micro-strip sensor
K. Solvag HK 34.8
11 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
Dileptons - electrons
• low-mass vector mesons: try to reject large physical background (-conversion, Dalitz decays) by high performance tracking
• J/: cut on pt (1.2 GeV/c)
• high purity of electron identification needed! (-suppr. > 104 achievable)
S/B=1.7
eff. 12%
J/ mesonlow-mass vector mesons
S/B = 0.2eff. 7.5%
T. Galatyuk HK 19.3
100k events = 10s of beam time
central Au+Au, 25 AGeV
1010 events
12 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
Dileptons - muons
• low efficiency for soft muons → investigate momentum dependent identification
• phantastic J/(pt > 1 GeV/c), even ' should be accessible
• however: high hit densities in detectors!
J/ meson
(add 1m Fe)
low-mass vector mesons (1.25 m Fe)
S/B = 0.4eff. 1.3% eff. 20%
A. Kiseleva HK 19.4central Au+Au, 25 AGeV
4∙108 events
13 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
First test beam data → hit density?
without Pb converter
with Pb converter (1.5 cm ~ 3X0)
• hit densities after absorbers? (reliability of simulation?)
• first results from test beam (6 GeV/c) at CERN, PS on high granularity gas detectors (ALICE prototypes):
→ increase hit density in GEANT 3 appr. by factor 2
ADC counts
14 Claudia Höhne DPG Frühjahrstagung, Gießen, März 2007
CBM collaboration
Russia:IHEP ProtvinoINR TroitzkITEP MoscowKRI, St. Petersburg
China:CCNU WuhanUSTC Hefei
Croatia: RBI, Zagreb
Portugal: LIP Coimbra
Romania: NIPNE Bucharest
Poland:Krakow Univ.Warsaw Univ.Silesia Univ. KatowiceNucl. Phys. Inst. Krakow
LIT, JINR DubnaMEPHI MoscowObninsk State Univ.PNPI GatchinaSINP, Moscow State Univ. St. Petersburg Polytec. U.
Ukraine: Shevchenko Univ. , Kiev
Cyprus: Nikosia Univ.
Univ. Mannheim Univ. MünsterFZ RossendorfGSI Darmstadt
Czech Republic:CAS, RezTechn. Univ. Prague
France: IPHC Strasbourg
Germany: Univ. Heidelberg, Phys. Inst.Univ. HD, Kirchhoff Inst. Univ. FrankfurtUniv. Kaiserslautern
Hungaria:KFKI BudapestEötvös Univ. Budapest
India:VECC KolkataSAHA KolkataIOP BhubaneswarUniv. ChandigarhUniv. VaranasiIlT Kharagpur
Korea:Korea Univ. SeoulPusan National Univ.
Norway:Univ. Bergen
Kurchatov Inst. MoscowLHE, JINR DubnaLPP, JINR Dubna
46 institutions
> 400 members
Strasbourg, September 2006
CBM related talks:
M. Klein-Bösing HK 16.8 T. Galatyuk HK 19.3A. Kiseleva HK 19.4 J. Heuser HK 22.2K. Solvag HK 34.8 D. Gonzalez-Diaz HK 47.4S. Gorbunov HK 53.1 C. Steinle HK 53.4
CBM related poster:
C. Müntz HK 49.23