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Simulation of a general purpose detector for the HESR project at GSI Darmstadt

Conceptual Design Report: http://www.gsi.de/GSI-Future. Simulation of a general purpose detector for the HESR project at GSI Darmstadt. V.Hejny* for the Antiproton Physics Study Group *Institut f ür Kernphysik, Forschungszentrum Jülich. Why experiments with antiproton beams ?

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Simulation of a general purpose detector for the HESR project at GSI Darmstadt

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  1. Conceptual Design Report: http://www.gsi.de/GSI-Future Simulation of a general purpose detector for the HESR project at GSI Darmstadt V.Hejny* for the Antiproton Physics Study Group*Institut für Kernphysik, Forschungszentrum Jülich • Why experiments with antiproton beams ? • High Energy Storage Ring • Overview of the detector system • Simulation methods (Geant4, Pluto, Root) • Simulation results • Future tasks

  2. “the hadron” Why antiprotons ? • Strong interaction in the subnuclear regime: Quantum Chromodynamics (QCD) • high energies as << 1: perturbative QCD • low energies, hadrons as 1: non-perturbative QCD • Open questions: • quark confinement • masses of strong interacting complex systems • firm establishment of hybrids and glueballs • … pp – annihilation: (at 1.5 – 15 GeV/c) • particle – antiparticle production (qq, hyperon – antihyperon, …) • strange and charm quarks interpolates between the extreme QCD limits (as 0.3, relativistic effects small) • gluonic degrees of freedom produced with high probability (ref. LEAR/CERN)

  3. Physics program Structure of hadrons / interaction with nuclear matter • Charmonium spectroscopyPoster HK 12.4 direct formation of all cc states, resolution given by beam • Charmed hybrids and glueballsPoster HK 12.6 high probabilty for gluonic states in pp annihilation • Charmed mesons in matterPoster HK 12.1 extension of the existing programs (p,K) to the charm sector (D, J/, …) • Hypernuclear physicsPoster HK 12.7 hypernuclear states, medium effects, properties of hyperons • Further options: Poster HK 12.5 • CP violation in the DD system and in hyperon decays • Rare decays of D-mesons

  4. GSI Future & HESR High Energy Storage Ring (HESR): Momentum range 1.5 – 15 GeV/cMomentum spread 10-4 (with electron cooling < 8GeV/c: 10-5)Beam diameter 100 mm Antiprotons stored in ring 5 x 1010 Luminosity (pellet target) 2 x 1032 cm-2s-1 Integrated luminosity 10 pb-1/day

  5. Detector properties Basic request: Build a modular, multi-purpose spectrometer for neutral and charged particle detection over the relevant angular (4p?) and momentum range (<1 GeV/cup to 10 GeV/c ?). Demands: rate capability 2 x 107 annihilations/s particle discrimination g, e, m, p, K, p vertex reconstruction for D, K0s, L (s 100 mm) momentum reconstruction Dp/p  1 – 2 % total pp cross section  100 mb reaction cross sections nb range and smaller various trigger conditions (e+e-), (gg), (m+m-), (FF), (KK) ,…

  6. A (first) view of the detector

  7. Detector simulationin Geant4 direct output into ROOT files event generation(into ROOT files) Analysisin ROOT PLUTO++in ROOT results fast simulationin ROOT Simulation scheme: Tools: ROOT for data handling and analysis http://root.cern.ch PLUTO++ for event generation (ROOT library) http://www-hades.gsi.de/computingphase space / exp. distributions for certain reactions read in by Geant4 or processed directly in ROOT Geant4 for detailed detector simulations http://geant4.web.cern.ch/geant4currently used version: 4.4.0 linked with ROOT to use ROOT file I/O

  8. Detector components (a second view): target spectrometer forward spectrometer straw tubetracker mini driftchambers muon counter DIRC: Detecting InternallyReflectedCherenkov light iron yoke superconductivecoil electromagneticcalorimeter micro vertexdetector

  9. Detector components: MVD Micro Vertex Detector:(as implemented in Geant4) 200 mm 50 mm 7.2 mio. barrel pixels 50 x 300 μm 2 mio. forward pixels 100 x 150 μm

  10. s(DD0) = 51 mm s(DZ0) = 82 mm track y z x Detector components: MVD Demanded resolution:s 100 mmSimulation results: D0 Z0 Matches resolution for D, K0s, L identification !

  11. DIRC STT MVD Detector components: STT Straw Tube Tracker: example event: pp f f  4K

  12. Detector components: MDC Mini Drift Chamber: Resolution: 150 mm

  13. pp  J/y + F (s = 4.4 GeV/c2): Overall performance Track and momentumresolution: s(J/y) = 35 MeV/c2 s(F) = 3.8 MeV/c2 F K+K- J/y m+m-

  14. focal planewith lightsensors lightcone quartz slab particle Detector components: DIRC DIRC: Detecting Internally Reflected Cherenkov light Existing DIRC:BaBar @ SLAC working scheme:

  15. “the real picture” reaction pp  f f at s = 3.6 GeV/c2 K eff. p miss-id. Detector components: DIRC • Particle identification: • reconstruction of light cone • momentum reconstruction used: a) determination of the orientation of the light cone • b) calculation of particle mass from b and p

  16. Detector components: EMC Electromagneticcalorimeter: barrel backwardendcap forwardendcap

  17. Detector components: EMC e/p particle discrimination: Invariant mass resolution: Reaction: pp  J/y + h (s = 4.4 GeV/c2)m(h) = 0.501 GeV/c2s(h) = 0.020 GeV/c2

  18. p misidentification m identification Detector components: Muon counter Moun counter: Detector performance:

  19. ? p pp  p+p-K0sK0s  3p+ 3p- pp  J/y + X (s = 4.4 GeV/c2) p primaryvertex secondaryvertex Total acceptance:(geometry x detection eff. x reconstruction) J/y e+e- J/y m+m- Overall performance Reconstruction of a secondary vertex: suppressing of combinatorical background by momentum conservation: s(K0s) = 3 MeV/c2

  20. Summary and Outlook • Current status: • A general purpose detector for antiproton physics has to be designed for the GSI Future Project • Simulations are performed in a framework of Geant4, ROOT and PLUTO++ • The solenoid part (target spectrometer) is nearly fully implemented • Results show that the current design meets the requirements • Future tasks: • Completion of the detector implementation in Geant4 (forward spectrometer) • Setting up an easy-to-handle analysis framework for the simulation results • Intensive background simulations: Total annihilation cross section is 200 mb, typical reaction cross section is in the order of nb for each valid event  108 events have to be simulated to prove background suppression hardly to be handled by Geant4  fully ROOT based, fast simulation is in preparation Workshop on experiments with antiprotons at the GSI future facilityApril 5 to 6, 2002 at GSI(further information: http://www-wnt.gsi.de/pbar)

  21. Antiproton Physics Study Group T. Barnes8, D. Bettoni6, R. Calabrese6, W. Cassing5, M. Düren5, S. Ganzuhr1, A. Gillitzer7, O. Hartmann2, V. Hejny7, P. Kienle9, H. Koch1, W. Kühn5, U. Lynen2, R. Meier11, V. Metag5, P. Moskal7, H. Orth2, S. Paul9, K. Peters1, J. Pochodzalla10, J. Ritman5, M. Sapozhnikov3, L. Schmitt9, C. Schwarz2, K. Seth4, N. Vlassov3, W. Weise9, U. Wiedner12 1 Experimentalphysik I, Bochum 2 GSI, Darmstadt 3 JINR, Dubna 4 Northwestern University, Evanston 5 Universität Gießen 6 INFN, Ferrara 7 Institut für Kernphysik, FZ Jülich 8 University of Tennessee, Knoxville 9 Technische Universität München 10 Institut für Kernphysik, Mainz 11 Physikalisches Institut, Tübingen 12 ISV, Uppsala

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