Probing dense baryonic matter with timelike photons

1
Probing dense baryonic matter with time-like
photons

• Dilepton spectroscopy from 1 to 40 AGeV at GSI
  and FAIR
• Joachim Stroth
• Univ. of Frankfurt

2
The physics case

• What are the properties of dense nuclear matter?

Its macroscopic properties depend on the
microscopic structure!
3
The physics case

• Probe the electromagnetic structure of (hot) and
  dense nuclear matter in the time-like region!
• What is the relevant excitation spectrum as the
  matter density increases?
• Where are the limits of hadronic existence?

Partial restoration of chiral symmetry
Additional self-energy terms due to meson-baryon
coupling
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Probing the interior of compressed matter
Low-mass vector mesons In-medium spectral
functions
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The HADES spectrometer

• Geometry
• Full azimuth , polar angles 18o - 85o
• Pair acceptance ? 0.35
• About 80.000 detector channels
• Fast particle identification
• RICH CsI solid photo cathode, No? 80, C4F10
  radiator
• TOF (Scintillator rods)
• TOFino (Scintillator paddles) temporary
  solution, RPC in future
• Pre-Shower 18 pad chambers lead converters
• Momentum measurement
• ILSE, super conducting toroid Br 0.35 Tm
• MDC Multi-wire drift chamber, single cell
  resolution ? 100 mm

1 m
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(No Transcript)
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Experimental runs

• November 2001 commissioning run target 5
  
• CC 2 AGeV LVL1 triggered events (Mch.gt3)
  45 Mevents
• CC 1 AGeV LVL1 trigger
  7.3 Mevents
• full coverage with inner MDC chambers (Dp/p ? 10
  at 0.7 GeV/c)
• November 2002 CC 2 AGeV, commissioning and
  physics runs
• target 2 x 2.5, 56 LVL1 trigger 44 LVL2
  trigger 220 Mevents
• 6 outer drift chambers (MDC) in 4 sectors
• October 2003 pp commissioning run (1 GeV, 2
  GeV)
• full coverage with outer MDC III (4 MDC IV) (Dp/p
  ? 1.5 at 0.7 GeV/c)
• February 2004 pp 2GeV production run
• target 5 cm l-H2 400 Mevents
• August 2004 CC 1AGeV production run
• 3x1.5 target, 56 LVL1 trigger 44 LVL2
  trigger 650 Mevents

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Fast 2nd level trigger
up to 20 kHz LVL1Fast multiplicity trigger
full event information digitised.
on-line selection of electron candidates
Suppression 10 - 100
LVL2 triggered events are transported to mass
storage
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On-line off-line comparison

• Trigger condition used in November 2002 run
• At least one good electron candidate
• Ring matched with META hit
• Data rate reduced by 92
• Pair enhancement by factor of ? 9
• Single lepton efficiency of IPUs matching ?
  62(pairs 82)

No bias on data
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CC _at_ 2 A GeV "Nov02"
No Efficiency / Acceptance Correction
preliminary

• Minimal tracking analysis
• No in-medium contributions in the simulation.

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CC _at_ 1 A GeV Aug'04
No Efficiency / Acceptance Correction
All N- B- 2sqrt(NN--) S- N- - B-
very preliminary
Yield / 1 MeV/c2
M MeV/c2
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Meson-baryon coupling and in-medium spectral
functions
One possible scenario

• Starting in 2006!
• Precision spectroscopy at nuclear ground state
  density
• Invariant mass resolution with outer tracking is
  1 in the vector meson mass region

W.Schoen et al. Acta Phys.PolB27(1996)2959
M. Effenberger, Giessen
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Facility for Antiproton and Ion Research
FAIR
nuclear matter at high densities CBM experiment
Staged realization
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The future of dielectron spectroscopy at FAIR
Heavy ion collisions at interaction rates of up
to 107 Hz and beam energies from 2 to 40 GeV/u
CBM Detector
E gt 10 AGeV
Talk by Peter Senger on Wednesday
HADES
E lt 10 AGeV
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HADES acceptance at higher energies
Simulation
CC 2 AGeV
CC 8 AGeV
Ycm
Ycm
Ycm
Ycm
1 GeV/c
ThermalSource
1 GeV/c
Accepted
Electrons from po-Dalitz, h-Dalitz, r, w
(-Dalitz), f 40 of geometrical cross section
J. Novotny, HADES collaboration meeting 2003
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HADES with beam from SIS100
Simulation

• Compared to 2 A GeV
• acceptance 40 lower
• yields 2 orders of magnitude higher

17
Experimental concept
Detector configuration CBM experiment
High quality tracking to identify "background"
tracks (conversion, p0)

• Perform momentum measurement in a 1m3 volume with
  1 T magnetic field.
• Possibly a flexible configuration to optimize
  performance for different physics cases..
• Both options, electrons and muons are
  investigated.

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Dilepton spectroscopy at GSI and FAIR

• Final CC spectra 1 and 2 AGeV
• p, p, d, A on lH2, A
• AA heavy collision systems

2005

• AA medium up to 8-10 AGeV

2010

• Dilepton spectroscopy in AA at 10-40 AGeV

time year AC
2015
Systematic study of the microscopic properties of
dense baryonic matter
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The Collaboration

• Cyprus
• University of Cyprus
• France
• Institut de Physique Nucléaire d'Orsay
• Czech Republic
• Nuclear Physics Institute, Rez
• Czech Academy of Sciences, Rez
• Germany
• GSI, Darmstadt
• FZR, Dresden
• Johann Wolfgang Goethe-Universität Frankfurt
• Justus Liebig Universität Giessen
• Technische Universität München

• Italy
• INFN Catania
• Università di Catania
• INFN Milano
• Università di Milano
• Poland
• Jagiellonian University of Cracow
• Russia
• LHE at JINR, Dubna
• Institute for Nuclear Research, Moscow
• MEPHI, Moscow
• ITEP, Moscow
• Spain
• University of Santiago de Compostela
• Universidad de Valencia-CSIC

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The CBM Collaboration
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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Lepton candidate selection

• Events with lepton multiplicity ? 1 in LVL1
  triggered events 1.2
• Require META and RICH signal (LVL2)
• matching with fully reconstructed tracks

cut on b
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Signal to Background Nov02
preliminary
CC Nov 02
S/B
data simulation
Nee- - CB
S/B
CB
ltS/Bgt 41 (M lt 100 MeV/c2) ltS/Bgt 12 (M gt
100 MeV/c2)
inv. mass MeV/c2
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Dielectrons in CBM
R. Karabowicz, Kraków, CBM Collaboration Meeting
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Experiments with pion beams

• in-beam tracking of pions
• pp and pA reactions