Motivation; CBM experimental setup, MVD+STS; Open charm at SIS 100; He cooling (no Beam Pipe)
1 THE MUON DETECTION SYSTEM FOR THE CBM EXPERIMENT AT FAIR/GSI A. Kiseleva Helmholtz International...
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Transcript of 1 THE MUON DETECTION SYSTEM FOR THE CBM EXPERIMENT AT FAIR/GSI A. Kiseleva Helmholtz International...
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THE MUON DETECTION SYSTEM FOR THE CBM EXPERIMENT AT FAIR/GSI
A. Kiseleva
Helmholtz International Summer SchoolDense Matter In Heavy Ion Collisions and Astrophysics (DM2008)
July 14 – 26, 2008
2
Outline
FAIR project CBM experiment:
– setup– observables
The muon detection system for CBM– layout– feasibility studies for:
ρ, ω, φ J/ψ
Conclusions and next steps
3
FAIR: the international Facility for Antiproton and Ion Research
GSI: Gesellschaft für Schwerionenforschung
GSI/FAIR
4
FAIR: the international Facility for Antiproton and Ion Research
storage and cooler rings
• beams of rare isotopes• e – A Collider
• 1011 stored and cooled antiprotons
0.8 - 14.5 GeV
primary beams
• 5∙1011/s; 1.5-2 GeV/u; 238U28+
• factor 100-1000 increased intensity• 4x1013/s 90 GeV protons• 1010/s 238U 35 GeV/u (Ni 45 GeV/u)
secondary beams
• rare isotopes 1.5 - 2 GeV/u; factor 10 000 increased intensity • antiprotons 3(0) - 30 GeV
accelerator technical challenges
• rapidly cycling superconducting magnets• high energy electron cooling• dynamical vacuum, beam losses
5
Research programs at FAIR
Rare isotope beams: nuclear structure and nuclear astrophysicsnuclear structure far off stabilitynucleosynthesis in stars and supernovae
Beams of antiprotons: hadron physicsquark-confinement potentialsearch for gluonic matter and hybridshypernuclei
Nucleus-nucleus collisions: compressed baryonic matter baryonic matter at highest densities (neutron stars) phase transitions and critical endpointin-medium properties of hadrons
Short-pulse heavy ion beams: plasma physicsmatter at high pressure, densities, and temperaturefundamentals of nuclear fusion
Atomic physics, FLAIR, and applied researchhighly charged atomslow energy antiprotonsradiobiology
Accelerator physicshigh intensive heavy ion beamsdynamical vacuumrapidly cycling superconducting magnetshigh energy electron cooling
CBM experiment
Nucleus-nucleus collisions: compressed baryonic matter baryonic matter at highest densities (neutron stars) phase transitions and critical endpoint in-medium properties of hadrons
6
Physics case
• crossover transition from partonic to hadronic matter at small B and high T
• critical endpoint in intermediate range of the phase diagram • first order deconfinement phase transition at high B but moderate T
hea
t
compression
Predictions from lattice QCD:
7
CBM physics topics and abservables
In-medium modifications of hadronsIn-medium modifications of hadrons • onset of chiral symmetry restoration at high densities onset of chiral symmetry restoration at high densities ρρBB
• measure: measure: ρρ, , ωω, , φφ → e → e++ee-- / / μμ++μμ--
• open charm (D mesons) open charm (D mesons)
Strangeness in matter (strange matter?)Strangeness in matter (strange matter?)• enhanced strangeness production ?enhanced strangeness production ?• measure: K, measure: K, ΛΛ, , ΣΣ, , ΞΞ. . ΩΩ
Indications for deconfinement at high Indications for deconfinement at high ρρBB • anomalous charmonium suppression ?anomalous charmonium suppression ?• measure: J/measure: J/ψψ, , ψψ' ' → e→ e++ee-- / / μμ++μμ--,, D D00 → K → Kππ, D, D±± →→ K Kππππ • softening of EOS softening of EOS • measure flow excitation function measure flow excitation function
Critical point Critical point • event-by-event fluctuations
Color superconductivityColor superconductivity• precursor effects ?precursor effects ?
8
Dilepton sources in heavy-ion collisions
Searching for the onset of deconfinement
Investigation of dense baryonic matter using penetrating probes
shift
? broadening
? melting
? ...
?
In-medium modifications of low-mass vector mesons:
J/ψ dissociation in the QGP
? sequential melting of
ψ’ and J/ψ
? modifications of pt
distribution ? collective flow of
charmonium
? …
?
9
10-1 100 101 102 103 10410-6
10-4
10-2
100
102
104
AGS SPS RHIC HSD ' 99
__
D(c)
J/D(c)
KK+
+
Mul
tipl
icit
y
Au+Au (central)
Energy [A GeV]
Yields for central Au+Au at 25 AGeV
J/ψ(3095 MeV)
ρ0
(770 MeV)
ω(782 MeV)
φ(1020 MeV)
1.95×10-5 23 38 1.28
6%4.6×10-
5 9×10-5 2.9×10-
4
~1×10-6 ~1×10-
3
3.4×10-3
3.7×10-
4
multiplicity
branching ratio (μμ)
yield per event
φφJ/J/ψψ
ππ++
CBM
pion-to-charmonium ratio ~
109 !
W. Cassing, E. Bratkovskaya, A. SibirtsevNucl. Phys. A 691 (2001) 745
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Experimental requirements
high statisticshigh statistics large signal-to-background ratiolarge signal-to-background ratio good mass resolutiongood mass resolution large acceptance large acceptance high reconstruction efficiencyhigh reconstruction efficiency
160 p400 -
400 +
44 K+
13 K-
Central Au+Au collision Central Au+Au collision at 25 at 25 AAGeVGeV
(UrQMD + GEANT3)(UrQMD + GEANT3)
• up to 107 Au+Au reactions/sec (beam intensities up to 109 ions/s with 1 % interaction target)
• determination of (displaced) vertices with high resolution ( 50 m)
• identification of leptons and hadrons
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CBM for dimuon measurements
STSSTS MuChMuCh TRDTRD ToFToF
STSSTS track, vertex and track, vertex and momentum reconstruction momentum reconstruction
MuChMuCh muon identification muon identification
TRDTRD global tracking global tracking
RPC-ToFRPC-ToF time-of-flight measurement time-of-flight measurement
Measurements:charmonium – standard MuCh (13.5λI)
low-massvector mesons – compact MuCh (7.5λI)
GEANT3 model
STS
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Muon detector segmentation
max pad 44.8 44.8 mm2
space resolution: x – 12.8 mm, y – 12.8 mm
min pad 1.4 2.8 mm2
space resolution: x – 400 μm, y – 800 μm
Mikhail Ryzhinskiy, Saint-Petersburg State Polytechnical University
5% occupancy
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Simulations
Signals: multiplicities from Hadron-String Dynamics (HSD)
– ρ, ω, φ, η and ηDalitz
– J/ψ, Ψ'
Background: Ultrarelativistic Quantum Molecular Dynamics (UrQMD)
– central Au+Au at 25 AGeV
www.th.physik.uni-frankfurt.de/~brat/hsd.html
www.th.physik.uni-frankfurt.de/~urqmd/
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Muon reconstruction
J/ψμ+
μ-
S. Gorbunov, Kirchhoff Inst. f. Physik, Universität HeidelbergI. Kisel, GSI
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Results
Signal-to- Efficiency MassSignal-to- Efficiency Mass
Background (%) resolution Background (%) resolution
(S/B) ratio (MeV)(S/B) ratio (MeV)
ω ω 0.09 0.09 2 10 2 10
φφ 0.03 0.03 4 12 4 12
J/ψJ/ψ 18 13 21 18 13 21
Ψ'Ψ' 0.8 16 27 0.8 16 27
Central Au+Au collisions at 25 AGeV
signals
J/ψ
Ψ'
signals
J/ψ
Ψ'
background
signals
ρ
ω
φ
η
ηDalitz
signals
ρ
ω
φ
η
ηDalitz
background
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Analysis of background composition
compact MuCh (7.5λI) standard MuCh (13.5λI)
Masse of particles:μ – 106 MeV, π – 140 MeV, Κ – 498 MeV, p – 938 MeV
Central Au+Au collisions at 25 AGeV
17
Background rejection via mass determination
m2 =
β =
γ =
m2 = P2 ( - 1)
Lc × t
√1 – β2
1
(β × γ)2
P2
β2
1
(L, t) → (L, t) → ββ
ToF
m2 (GeV2/c4)
P (
GeV
/c)
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Improved results with pIDToF
610-3
510-4
without ToF with ToF
Central Au+Au collisions at 25 AGeV
compact MuCh (7.5λI)
S/B ratio eff.%
0.09 2.0
0.03 4.1
S/B ratio eff.%
0.17 1.5
0.06 3.0
ω
φ
19
Results for different collision systems
central Au+Au central Au+Au @ 25 @ 25 AAGeVGeV
central Au+Au @ central Au+Au @
8 8 AAGeVGeV
central central p+C p+C
@ 30 @ 30 AAGeVGeV
ωωToF pIDToF pID J/J/ψψ ωωToF pIDToF pID J/J/ψψ ωω J/J/ψψ
S/BS/B 0.170.17 1818 0.14 0.14 (0.09)*(0.09)*
–– 1111 147147
εε, , %%
1.51.5 1313 0.8 0.8 (1.2)*(1.2)* –– 44 2323
* in order to increase the acceptance of reconstructed ω we can use different type of tracks
20
Study of possible detector solutions
Detector requirements:Detector requirements: high rate capability (up to 1 MHz/cmhigh rate capability (up to 1 MHz/cm22) ) high granularity (up to 1 hit/cmhigh granularity (up to 1 hit/cm22ss-1 -1 for central Au+Au for central Au+Au
collisions)collisions) position resolution < 300 position resolution < 300 μμmm
Detector options:Detector options: GEMGEM
((Gas Electron Multiplier))
MicromegasMicromegas ((Micro Mesh Gaseous Detector)
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Detector prototypes: GEMs
LHE JINR Dubna
PNPI St. PetersburgPNPI St. Petersburg
VECC KolkataVECC Kolkata
Support structure
PadsPads
FastenersFasteners
SpacerSpacer
PCBPCB Readout electronicsReadout electronics
ArgonArgon
GEM foilsGEM foils
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Conclusions
Promising results for low-mass Promising results for low-mass vector mesons vector mesons
Good result for J/Good result for J/ψψ
ψψ' identification seems possible ' identification seems possible
23
Next steps
Implementation of muon triggerImplementation of muon trigger Realistic detector response:Realistic detector response:
– clustering clustering – realistic detector inefficiencyrealistic detector inefficiency
Muon system optimization:Muon system optimization:– necessary number of detector layersnecessary number of detector layers– additional absorber in STSadditional absorber in STS– detector resolution studydetector resolution study
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Thank youfor your attention!
China
Croatia
Cyprus
Czech Republic
France
Germany
Hungaria
India
Korea
Norway
Poland
Portugal
Romania
Russia
Ukraine
China
Croatia
Cyprus
Czech Republic
France
Germany
Hungaria
India
Korea
Norway
Poland
Portugal
Romania
Russia
Ukraine52 institutions, more than 400 members (May 2008)
www.gsi.de/fair/experiments/CBM/index.html
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Signal acceptance
J/ψ→μ+μ-
ρ→μ+μ-
Pluto
Pluto
STS
STS
1m Fe
1m Fe
Central Au+Au collisions at 25 AGeV
27
Signal parameters: J/ψ
J/ψ
Bg
Bg J/ψ
2
(central Au+Au at 25AGeV)
28
Signal parameters: ρ0
ρ0
Bg
Bg ρ0
2
(central Au+Au at 25AGeV)
29
Hard-soft pairsρ0→μ+μ-
— hard-hard (h-h) pairs
— hard-soft (h-s) pairs
— h-h + h-s
μhard
μsoft
30
Digitization algorithm
primary electrons
sec. electron
s
Advanced digitization and cluster finding in MuCh, M. Ryzhinskiy