ICPAGQP 2005, Kolkata Probing dense baryonic matter with time-like photons Dilepton spectroscopy from 1 to 40 AGeV at GSI and FAIR Joachim Stroth Univ. of Frankfurt

ICPAGQP 2005, Kolkata Toneev et al., 2004 The physics case What are the properties of dense nuclear matter? Dense matterFreeze-out First chance collisions Its macroscopic properties depend on the microscopic structure!

ICPAGQP 2005, Kolkata 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? Additional self-energy terms due to meson- baryon coupling J. Wambach et al. Dense baryonic matter Partial restoration of chiral symmetry

ICPAGQP 2005, Kolkata Probing the interior of compressed matter p n  ++  K   p e+e+ e-e-  Low-mass vector mesons In-medium spectral functions

ICPAGQP 2005, Kolkata The HADES spectrometer Geometry ûFull azimuth, polar angles 18 o - 85 o ûPair acceptance  0.35  About detector channels Fast particle identification  RICH CsI solid photo cathode, N o  80, C 4 F 10 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 B  = 0.35 Tm  MDC Multi-wire drift chamber, single cell resolution  100  m 1 m

ICPAGQP 2005, Kolkata

Experimental runs November 2001: commissioning run target = 5% 45 Mevents –C+C 2 AGeV LVL1 triggered events (M ch. >3) : 45 Mevents 7.3 Mevents –C+C 1 AGeV LVL1 trigger : 7.3 Mevents –full coverage with inner MDC chambers (  p/p  10% at 0.7 GeV/c) November 2002: C+C 2 AGeV, commissioning and physics runs 220 Mevents –target= 2 x 2.5%, 56% LVL1 trigger + 44% LVL2 trigger 220 Mevents –6 outer drift chambers (MDC) in 4 sectors October 2003: p+p commissioning run (1 GeV, 2 GeV) –full coverage with outer MDC III (4 MDC IV) (  p/p  1.5 % at 0.7 GeV/c) February 2004: p+p 2GeV production run 400 Mevents –target 5 cm l-H Mevents August 2004: C+C 1AGeV production run 650 Mevents –3x1.5 % target, 56% LVL1 trigger + 44% LVL2 trigger650 Mevents

ICPAGQP 2005, Kolkata Fast 2 nd level trigger up to 20 kHz LVL1 Fast multiplicity trigger full event information digitised. on-line selection of electron candidates LVL2 triggered events are transported to mass storage Suppression

ICPAGQP 2005, Kolkata 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%) M e+e- [MeV/c 2 ] Yield /event [a.u]  e+e- > 4 0 Scaled down by 9.2 ! LVL2 LVL1 No bias on data

ICPAGQP 2005, Kolkata 2 A GeV "Nov’02" preliminary No Efficiency / Acceptance Correction Minimal tracking analysis No in-medium contributions in the simulation.

ICPAGQP 2005, Kolkata 1 A GeV “Aug'04” All N+- B+- = 2*sqrt(N++*N--) S+- = N+- - B+- M [MeV/c 2 ] Yield / 1 MeV/c 2 very preliminary No Efficiency / Acceptance Correction

ICPAGQP 2005, Kolkata Meson-baryon coupling and in-medium spectral functions Starting in 2006! Precision spectroscopy at nuclear ground state density Invariant mass resolution with outer tracking is 1 % in the vector meson mass region M. Effenberger, Giessen One possible scenario  e+ e- 208 Pb -- n W.Schoen et al. Acta Phys.PolB27(1996)2959

ICPAGQP 2005, Kolkata nuclear matter at high densities CBM experiment Facility for Antiproton and Ion ResearchFAIR Staged realization

ICPAGQP 2005, Kolkata The future of dielectron spectroscopy at FAIR Heavy ion collisions at interaction rates of up to 10 7 Hz and beam energies from 2 to 40 GeV/u CBM Detector HADES E < 10 AGeV E > 10 AGeV Talk by Peter Senger on Wednesday

ICPAGQP 2005, Kolkata e+e+ e-e- e+e+ e-e- HADES acceptance at higher energies Thermal Source Accepted Y cm Y ptpt C+C 2 AGeVC+C 8 AGeV 1 GeV/c J. Novotny, HADES collaboration meeting 2003 Electrons from:  o -Dalitz,  -Dalitz, ,  (-Dalitz),  40 % of geometrical cross section Simulation

ICPAGQP 2005, Kolkata HADES with beam from SIS100 Compared to 2 A GeV –acceptance 40% lower –yields 2 orders of magnitude higher Simulation

ICPAGQP 2005, Kolkata Experimental concept Perform momentum measurement in a 1m 3 volume with 1 T magnetic field. Possibly a flexible configuration to optimize performance for different physics cases.. electrons muons Both options, electrons and muons are investigated. Detector configuration CBM experiment High quality tracking to identify "background" tracks (conversion,  0 )

ICPAGQP 2005, Kolkata Dilepton spectroscopy at GSI and FAIR ×Final C+C spectra 1 and 2 AGeV  , p, d, A on lH 2, A ×A+A heavy collision systems time [year AC] ×Dilepton spectroscopy in A+A at AGeV ×A+A medium up to 8-10 AGeV Systematic study of the microscopic properties of dense baryonic matter

ICPAGQP 2005, Kolkata 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

ICPAGQP 2005, Kolkata 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

ICPAGQP 2005, Kolkata Lepton candidate selection Events with lepton multiplicity  1 in LVL1 triggered events: 1.2 % üRequire META and RICH signal (LVL2) ü+ matching with fully reconstructed tracks linear z axis ! log. z axis ! yield [arb. units] cut on 

ICPAGQP 2005, Kolkata Signal to Background Nov02 preliminary N e+e- - CB CB S/B = ~ 4:1 (M < 100 MeV/c 2 ) ~ 1:2 (M > 100 MeV/c 2 ) inv. mass [MeV/c 2 ] S/B Mass range [MeV/c2]: 0 -> > > 1000 Signal e+e- pairs data simulation C+C Nov ‘02

ICPAGQP 2005, Kolkata Dielectrons in CBM R. Karabowicz, Kraków, CBM Collaboration Meeting

ICPAGQP 2005, Kolkata Experiments with pion beams in-beam tracking of pions  p and  A reactions E thresh [GeV] M x [GeV/c 2 ]   //  pp->ppX  - p->Xn