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Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Charmed Hadrons in Matter
• Introduction
• Medium Effects in the light quark sector
• Expectations for the charm quark sector
• J/ψ-N interaction
• Requirements for the Experiment
• Conceptual Design
• Conclusions
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Introduction
Origin of Hadron Masses ?
Chiral Symmetry in QCD is spontaneously broken
Mass Modifications due to
• Chiral Dynamics
• Partial Restoration of C.S. in Hadronic Environment
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Deeply bound Pionic States
• 206Pb(d,3He)Pion-Nucleus Potential from binding energy and width
isospinasymmetric matter, ρ ρ0
m(π-) increased by 25 MeV
A. G
illitz
er, H
irsch
egg
‘01
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Production of Open Strangeness
• Excitation functionfor K+/K- productionin H.I. Reactions
• Different from elementary reaction:enhanced σ(K-)
• K- mass loweredby 100 MeV (ρρ0) F. L
aue,
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Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Expectations for charmed Mesons
• J/ψ, ηc: -5 to -10 MeV• D-Mesons
“Hydrogen of QCD”
- mass lowering- 50 MeV mass split
Charm quark mass: 1.3-1.5 GeV
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Consequences for Observables
A. S
ibirt
sev
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• DD production will be enhanced below threshold
• D-mesons decay semi-leptonic (10-20% BR)
• Cross sections 1 nb near threshold
• D,D,Ds,Ds,J/ψ,ψ’
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Consequences for Observables II
Threshold lowered by 100 MeV “new” decay channels open (ψ’,χc2) width increases
ψ(3770) broadening(lepton pair detection)
A. H
ayas
higa
ki P
LB48
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Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
J/ψ-N Absorption Cross Section
• In URHIC: suppression of J/ψ observed
? Hadronic Interactions?• 3-4 mb from γN
6-7 mb from pA, AA Antiproton annihilation on
nuclei
• also for J/ψ, ψ’, χJ
on various nuclear targets
K.K
. Set
h, H
irsch
egg
‘01
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Dissociation of Charmonium
• p + d D- + Λc+
• cc interacts with residual neutron
• Studying energy dependence
p + d J/ψ + + n: measuring σ(J/ψ-N)elastic down to lower relative momenta
• J/ψ -meson scattering cross section
A. S
ibirt
sev
NP
A68
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Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Requirements for the Experiment
• Production of charmed mesonsσ(DD) 1 nb 100 d-1 @ L = 2·1031 cm-2s-1
high luminosity
• c(D±) = 315 µm, c(DS) = 149 µm well-defined interaction point good vertex resolution ( 100 µm )
• D’s decay semileptonic (10 – 20 % B.R.)decay kinematics: high pt, large opening angles momentum determination, PID
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Microvertex Tracking
Silicon Pixel Detector, 200 µm wafers (0.25% X0)
7.2 MPixels50·300 µm²
2 MPixels100·150 µm²
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Microvertex Tracking II
Does the concept meet the requirements?
σ(D0) = 50 µm
σ(Z0) = 85 µm
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Momentum determination, PID
• Straw Tubes for trackingσxy = 150µm, σz = 1mm
• Drift chambers• Separation of π/K
(DIRČ)
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Lepton identification
• Electromagnetic calorimeter (PbWO4)
96% coverage of the
solid angle• Muon hodoscope
(plastic scintillators)
Workshop on Experiments with Antiprotons at the HESR – April 2002, GSI
Conclusions
• GSI has a successful history in studying medium effects in the light quark sector
• Extending the program to the charm quark sector promises exciting perspectives
• The proposed program requires a versatile detector in terms of resolution, PID, rate capability and triggering