The Compressed Baryonic Matter experiment at the future accelerator facility in Darmstadt Claudia Höhne GSI Darmstadt, Germany

Claudia Höhne NPDC 18 Prague nuclei hadronic phase SPS RHIC lattice QCD : Fodor / Katz, Nucl. Phys. A 715 (2003) 319 SIS300 dilute hadron gas dense baryonic medium Motivation Phase diagram of strongly interacting matter high T, low  B  top SPS, RHIC, LHC low T, high  B  SIS intermediate range ?  low energy runs SPS, AGS  SIS GSI ! Highest baryon densities Critical point? Deconfinement?

Claudia Höhne NPDC 18 Prague Motivation SIS300 light, heavy ions Phase diagram of strongly interacting matter high T, low  B  top SPS, RHIC, LHC low T, high  B  SIS intermediate range ?  low energy runs SPS, AGS  SIS GSI ! Highest baryon densities Critical point? Deconfinement? and region of maximum of relative strangeness production

Claudia Höhne NPDC 18 Prague Motivation [Allton et al., Phys. Rev. D68, (2003)] [Allton et al., Phys. Rev. D66, (2002)] *[Fodor, Katz, JHEP 0404, 050 (2004)]  q /T=1 critical point * recent improvements in lattice-QCD allow for calculations at finite  B : large baryon-number density fluctuations at the phase border for  q /T=1 critical point at T E =162  2 MeV,  E =360  40 MeV *  intermediate range of phase diagram!

Claudia Höhne NPDC 18 Prague Known so far... Low energy run at SPS (20, 30, 40 AGeV): Relative strangeness production shows... sharp maximum in energy dependence: transition from hadronic to partonic phase? dynamical fluctuations which increase towards lower energies: critical point? [J. Phys. G 30, 1381 (2004)] NA49 [J. Phys. G 30, 701 (2004)]

Claudia Höhne NPDC 18 Prague Known so far... Low energy run at SPS (40 AGeV):   e + e - enhancement of low-mass dilepton pairs, larger at 40 AGeV compared to 158 AGeV in medium modification of  ?  need more and better measurements also at lower energies! CERES [Phys. Rev. Lett. 91, (2003)]

Claudia Höhne NPDC 18 Prague Known so far... A+A collisions at SIS : strangeness production in medium [M. Lutz, Phys. Lett. B 426, 12 (1998)] KAOS Collaboration experimental evidence for modification of kaon energy in medium! yields, rapidity spectra, azimuthal distributions... K+K+ RBBU KN Pot. no KN Pot.

Claudia Höhne NPDC 18 Prague Open questions... various QCD inspired models predict a change of the D-mass in a hadronic medium in analogy to kaon mass modification, but drop for both, D + and D - substantial change (several 100 MeV) already at  =  0 effect for charmonium is substantially smaller [Mishra et al., Phys. Rev. C 69, (2004) ]

Claudia Höhne NPDC 18 Prague Open questions... Consequence of reduced D mass: DD threshold drops below charmonium states [Mishra et al., Phys. Rev. C 69, (2004) ] decay channels into DD open for  ’,  c, J/   broadening of charmonium states  suppression of J/   lepton pair channel (large fraction of J/  from higher states)  (slight) enhancement of D mesons

Claudia Höhne NPDC 18 Prague Open questions but even charm production near threshold is not known [Gorenstein et al J. Phys. G 28 (2002) 2151] central Au+Au Predictions of open charm yield for central A+A collisions differ by orders of magnitude for different production scenarios, especially at low energies [W. Cassing et al., Nucl. Phys. A 691, 753 (2001)]

Claudia Höhne NPDC 18 Prague CBM experiment physics topics observables deconfinement at high  B ? softening of EOS ? strangeness production: K,  charm production: J/ , D flow excitation function Critical point ?event-by-event fluctuations   e + e - open charm in-medium properties of hadrons  onset of chiral symmetry restoration at high  B

Claudia Höhne NPDC 18 Prague CBM experiment observables detector requirements strangeness production: K,  charm production: J/ , D flow excitation function event-by-event fluctuations   e + e - open charm all-in-one device suitable for every purpose tracking in high track density environment (~ 1000) hadron ID lepton ID myons, photons secondary vertex reconstruction (resolution  50  m) large statistics: high beam intensity (10 9 ions/sec.) high interaction rates (10 MHz) fast, radiation hard detector efficient trigger rare signals!

Claudia Höhne NPDC 18 Prague CBM detector layout tracking, vertex reconstruction: radiation hard silicon pixel/strip detectors (STS) in a magnetic dipole field electron ID: RICH1 & TRD (& ECAL)   suppression  10 4 hadron ID: TOF (& RICH2) photons,  0,  : ECAL high speed DAQ and trigger beam targetSTS TRDs TOF ECAL RICHs magnet

Claudia Höhne NPDC 18 Prague SIS 100 Tm SIS 300 Tm U: 35 AGeV p: 90 GeV FAIR Facility for Antiproton and Ion Research „next generation“ accelerator facility: double-ring synchrotron simultanous, high quality, intense primary and secondary beams cooler/ storage rings (CR, NESR, HESR) Ion and Laser induced plasmas: High energy density in matter Compressed baryonic matter Cooled antiproton beam: hadron spectroscopy Structure of nuclei far from stability

Claudia Höhne NPDC 18 Prague Tracking with STS Experimental conditions: 5cm (1st STS) up to 2 hits/mm 2 per event 100cm (7th STS) < 0.01 hits/mm 2  7 planar layers of pixel/ strip detectors: high precision vertex reconstruction: 2 pixel layers at 5cm, 10 cm downstream of target fast strip detectors for outer stations (20, 40, 60, 80, 100 cm from target) Reconstruction efficiency > 95 % Momentum resolution ≈ 0.6 % fraction of reconstructed tracks p [GeV/c]

Claudia Höhne NPDC 18 Prague STS Requirements: radiation hardness low material budget: d < 200  m fast read out good position resolution < 20  m MIMOSA IV IReS/ LEPSI Strasbourg R&D on Monolithic Active Pixel Sensors (MAPS): pitch 20  m thickness < 100  m single hit resolution ~ 3  m problem: radiation hardness and readout speed (  event pile up in first 2 STS) fallback solution: hybrid detectors (problem: thickness, granularity!)

Claudia Höhne NPDC 18 Prague electron ID with RICH 1 radiator gas: N 2   th = 41, p ,th = 5.7 GeV/c  (almost) hadron blind photodetectors: photomultipliers (or gas detectors) aim:  suppression ~  -spectrum at for central Au+Au collision at 25 AGeV (UrQMD)

Claudia Höhne NPDC 18 Prague RICH 1 two mirrors: beryllium covered with glass, R = 450 cm two focal planes (3.6 m 2 each) separated vertically, shielded by magnet yoke layout RICH: side view z (beam) y rings in focal plane

Claudia Höhne NPDC 18 Prague TRD Task: e/  separation > 100, tracking Setup: 9 layers in three stations (4m, 6m, 8m from target) area per layer 25, 50, 100 m 2  efficiency < 1% reachable with 9 layers: R&D for most of the system state-of-the art is appropriate (ALICE) inner part: R&D on fast gas detectors in progress (drift chamber/ GEM/ straw tubes) Requirements: high counting rate (up to 150 kHz/cm 2 ) fast readout (10 MHz) large area position resolution ~ 200  m

Claudia Höhne NPDC 18 Prague Hadron ID with TOF bulk of hadrons ( , K, p) can be well identified with  TOF = 80 – 100 ps identification probability of K - for  TOF = 80 ps

Claudia Höhne NPDC 18 Prague RPC as TOF detector Challenge for TOF : high counting rate (25 kHz/cm 2 ) large area (130 m 10 m) time resolution ~ 80 ps R&D Coimbra, Portugal prototype: single gap counters with metal and plastic electrodes (resistivity 10 9  cm)

Claudia Höhne NPDC 18 Prague RICH 2 (?) Kaon ID by TOF quickly deteriorates above 4 GeV Option for RICH2 ? e.g.  thr = 30  p ,thr = 4.2 GeV, p K,thr =15 GeV problem: ring finding in high hit density environment Kaon ID by RICH for p > 4 GeV would be desirable identification probability of K - for  TOF = 80 ps Momentum distribution of kaons from D 0 decays

Claudia Höhne NPDC 18 Prague DAQ & trigger architechture Requirements efficient detection of rare probes (D, J/ , low-mass dilepton pairs): event rate 25 kHz  evaluation of complex signatures fast: 1st level trigger at full design interaction rate of 10MHz  reconstruct ~ 10 9 tracks/s, secondary vertices... data volume in 1st level trigger ~ 50 Gbytes/s event size ~ 40kbyte clock Detectors Frontend electronics Buffer pool Event builder and selector storage (1Gbyte/s) self-triggered hit detection pre-processing feature extraction each hit transported as address/ timestamp/ value extraction of physical signatures trigger decision essential performance limitation not latency but throughput

Claudia Höhne NPDC 18 Prague Feasibility Study: D 0 Key variable to suppress background: secondary vertex position D 0  K -  + (c  =124.4  m, BR 3.9  0.1%) central 25 AGeV (HSD): ~ simulation including various cuts (v z !)  S/B ~ 1  detection rate ~ 13k/h at 1MHz interaction rate Crucial detector parameters material in STS single hit resolution

Claudia Höhne NPDC 18 Prague Feasibility Study: J/  e + e - extremely rare signal (central 25 AGeV ~ /event) 6% branching ratio  e + e - background from various sources: conversion, Dalitz decays of  0 and , , misidentified  very efficient cut on single electron p t, pair opening angle S/B > 1 should be feasible

Claudia Höhne NPDC 18 Prague Feasibility Study:   e + e - branching ratio ~ (  ) – (  ) background from various sources: conversion, Dalitz decays of  0 and , misidentified  no easy p t -cut as for J/  sophisticated cutting strategy necessary depends crucially on elimination of conversion pairs by tracking and charged pion discrimination by RICH and TRD (  10 4 !) idealized simulation: no momentum resolution no  misidentification cut on p t, pair opening angle, prim. vertex track  S/B 0.5-1

Claudia Höhne NPDC 18 Prague Status of project So far... November 2001Conceptual Design Report, Cost estimate 675 M € July 2002German Wissenschaftsrat recommends realisation February 2003German Federal Gouvernment decides to build the facility, will pay 75% January 2004CBM Letter of Intent submitted CBM collaboration is formed: 250 scientiest from 39 institutions work in progress: detector design and optimization R&D on detector components feasibility studies of key observables next step: Technical Proposal January 2005 could run in 2012!

Claudia Höhne NPDC 18 Prague 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 Romania: NIPNE Bucharest 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 PNPI Gatchina SINP, Moscow State Univ. Spain: Santiago de Compostela Univ. Ukraine: Univ. Kiev Hungaria: KFKI Budapest Eötvös Univ. Budapest Italy: INFN Frascati Korea: Korea Univ. Seoul Pusan National Univ. Norway: Univ. Bergen Poland: Jagiel. Univ. Krakow Silesia Univ. Katowice Warsaw Univ. Warsaw Tech. Univ. Portugal: LIP Coimbra

Claudia Höhne NPDC 18 Prague CBM time schedule Subproject Si-Tracker RICH TRD TOF-RPC ECAL Trigger/DAQ Electronics Magnet Infrastructure simulations, R&D, designPrototypingConstructionInstallation, test Milestones: 1. Technical Proposal begin of Technical Design Report end of 2007

Claudia Höhne NPDC 18 Prague Hit rates for 10 7 minimum bias Au+Au collisions at 25 AGeV: Rates of > 10 kHz/cm 2 in large part of detectors !  main thrust of our detector design studies experimental conditions

Claudia Höhne NPDC 18 Prague CBM R&D working packages Feasibility, Simulations D  Kπ(π) GSI Darmstadt, Czech Acad. Sci., Rez Techn. Univ. Prague ,ω,   e + e - Univ. Krakow JINR-LHE Dubna J/ψ  e + e - INR Moscow Hadron ID Heidelberg Univ, Warsaw Univ. Kiev Univ. NIPNE Bucharest INR Moscow GEANT4: GSI Tracking KIP Univ. Heidelberg Univ. Mannheim JINR-LHE Dubna Design & construction of detectors Silicon Pixel IReS Strasbourg Frankfurt Univ., GSI Darmstadt, RBI Zagreb, Univ. Krakow Silicon Strip SINP Moscow State U. CKBM St. Petersburg KRI St. Petersburg RPC-TOF LIP Coimbra, Univ. Santiago de Com., Univ. Heidelberg, GSI Darmstadt, Warsaw Univ. NIPNE Bucharest INR Moscow FZ Rossendorf IHEP Protvino ITEP Moscow Fast TRD JINR-LHE, Dubna GSI Darmstadt, Univ. Münster INFN Frascati Straw tubes JINR-LPP, Dubna FZ Rossendorf FZ Jülich Tech. Univ. Warsaw ECAL ITEP Moscow GSI Darmstadt Univ. Krakow RICH IHEP Protvino GSI Darmstadt Trigger, DAQ KIP Univ. Heidelberg Univ. Mannheim GSI Darmstadt JINR-LIT, Dubna Univ. Bergen KFKI Budapest Silesia Univ. Katowice Univ. Warsaw Magnet JINR-LHE, Dubna GSI Darmstadt Analysis GSI Darmstadt, Heidelberg Univ, Data Acquis., Analysis

Claudia Höhne NPDC 18 Prague Acceptance of D 0 and J/  p t [GeV/c] D0D0 J/ψ

Claudia Höhne NPDC 18 Prague  misidentification 0 % 1 %0.1 % 0.01 %

Claudia Höhne NPDC 18 Prague Granularity: inner region 2x2 cm 2 intermediate region 5x5 cm 2 outer region 10x10 cm 2 Lead-scintillator calorimeter: 0.5 – 1 mm thick tiles 25 X 0 total length PM read out Distance between electron and closest track in the innermost region Tests of detector module prototype: July 2004 at CERN Design of ECAL Design goals of sampling calorimeter: energy resolution of 5/  E (%) high-rate capability up to 15 kHz/cm 2 e/  /(  ) discrimination of total area ~200m 2

Claudia Höhne NPDC 18 Prague GSI