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The HADES experiment @GSI

The HADES experiment @GSI. Collaboration: 18 Inst. 125 members. Motivation Detector description Performance outlook. Motivation. Properties of hadrons in strong int. matter: M, G vs r , m B , T, V Vector meson , ,  spectral functions measurements

hilary-crawford
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The HADES experiment @GSI

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  1. The HADESexperiment @GSI Collaboration: 18 Inst. 125 members • Motivation • Detector description • Performance • outlook

  2. Motivation • Properties of hadrons in strong int. matter: M, G vsr, mB, T, V • Vector meson , ,  spectral functions measurements • Hadron’s structure: VDM, Form factors, vector meson-nucleon inter. • Dalitz and two-body decays, pN, N reactions • SIS / GSI : heavy ion, proton,pion beams • 0 r 3 r00  T  80 MeV • HADES: systematic dielpton spectroscopy • meson prod. in pp / pp : r = 0 , T = 0 MeV • meson prod. in pA / pA : r = r0 , T = 0 MeV • meson prod. in AA : r = 1-3r0 , T = 80MeV

  3. High Acceptance DiElectron Spectrometer Magnet SC. toroid ( 6 coils) • 2p in f18o < J < 85o Lepton Identification • RICH C4F10 + gas Phot. Det. CsI - cathode • META TOF scintillator wall + • Pre-Shower detector p/ identification META and tracking Tracking p – measurement, vertex reconstruction MDCDrift chambers dx ~ 80 mm (s)

  4. PreShower Magnet Coils HADES@GSI RICH RICH +MDC I Back view

  5. SC Toroid • Imax = 3465 A • Bmax = 3.7 T • Bmax = 0.7 T Dp (q=25°) = 103 MeV/c Dp (q=80°) = 60 MeV/c • Beam operation • I = 2500 A Dp (25°) = 74 MeV/c coil air HADES S.C. Magnet ILSE

  6. Ring Imaging CHerenkov Detector e+e- - identification • Cherenkov light • cos qc= 1/ ß.n(l) • N = N0. lrad.1/ gt2 ( lrad = 40 cm ) • N0 det. characteristics • Radiator (hadron blind!) • 3 ~ ghad < gt < glep • C4F10 : gt = 18.3 • pp> 3 GeV/c • VUV - MirrorPoly-C substr. (2 mm) x/X < 2% Al + MgF2 coating R > 80% • Photon detector (MWPC) CsI - cath. • CaF2 window

  7. RICH in parts Photon detector with CaF2 window & CFK radiator shell

  8. g g e+ e+ Q~ 0.70 p0 Q~ 2.20 e- Conversion e- Dalitz RICH rings Strong sources lead to large comb. backgr.!!!

  9. Multiwire Drift Chambers • 0.7 % mass resolution in the r/w - region • Combinatorial background reduction – e+,e- close pair rejection

  10. IPN Orsay LHE Dubna FZR GSI Multiwire Drift Chambers • 4 layer/sector. • total 33 m3 active area, 27000 cells • y<100 m plane resolution • He-iC4H10 [60-40]gas mixture and low Z material GSI plane ORSAY plane • MDC: participating Institutions: • I: GSI, • II: LHE/JINR Dubna, • III: FZ Rossendorf, • IV: IPN Orsay

  11. x/X0  5 10-4 MDC module Cell characteristic 6 [mm]

  12. Performance of MDC Orsay Spatial Resolution (microns) GSI Dubna FZR Chamber Number • Intrinsic spatial resolution: • Proton beam, silicon tracker • “In-beam” (C+C 1.8 AGeV) Layer efficiency: > 98%

  13. Daughterboards MDC Read-out ASD8 LVL1-connector FPC- connector TDC Motherboard • TDC Features: (8 channels per chip) • 8 channels per chip • 250/500 ps/channel • “2 times (t1, t2) – multi-hit capable • Zero & spike (t1-t2 < 20ns) suppression • Calibration Mode (…mixed trigger • “Time above threshold” (…signal shape, charge): • Efficient Offline noise suppression! • Analog Read-out: • Differential amplifier, ASD8 chip, 8 channels, • 1 fC intr. Noise, 30 mW/channel • adjustable threshold (one for 16 channels)

  14. TOF>450 Ch. p. distribution for C+C @ 1.5 AGeV Outer TOF wall >450: • 6 * 64 scint. Installed. • T line fully operational • dt : 90 – 140 ps • dE/dx measurement • tracking J. Friese, TU München

  15. counts p [MeV/c] deuterons b Mass [MeV/c2] counts Tof [ns] Mass [MeV/c2] Energy loss [MeV] TOF-hadron identification Preliminary Deuteron peak: m0 = 1890 MeV sm = 551 MeV protons

  16. TOF-RICH lepton identification

  17. Pre-Shower/TOF system <450 Pre-Shower Pre-conv Post1-conv Post2-conv. esingle80% Pads TOFINO • tof measurement t0.35 ns Field Sense wires 2 radiation lengths Pb converter target Pre-Shower detector side view beam • 3 pad chambers (20000 pads) • em. showers in Pb converters

  18. C+C1.5 AGeV One event: detector response Pre-converter Post1-converter Post2-Converter p beam e- beam Shower candidate Pre-Conv Pre-Conv Post1-Conv Post1-Conv

  19. RICH-MDC-META lepton identification Data: Nov01C-C 2.0 AGeV magnetic field preliminary q* momentum Log z! tof [ns] tof [ns] q*momentum

  20. RICH-MDC-META lepton identification Data: Nov01C-C 2.0 AGeV magnetic field preliminary • Full HADES simulation and data analysis • RQMD ev.generator simul. Ne/N+ RICH-Track(MDC-META) • RICH & fast tof &shower • MDC I/II (inner ) e- e+ q* momentum [e*MeV/c]

  21. HADES Trigger System • Needslevel 2 trigger: • Ring recognition in RICH • Hit finding and tof calculation in TOF • El. Shower search in Pre-Shower RICH and META candidate matching via azimuthal correlations • Selection of e+e--pairs(momentum and invariant mass analysis) • High rates (105 Hz) • 10ms max. LVL2 trigger decision time) • Parallel- und Pipeline architecture FPGAs, CPLDs andDSPs • 107- 108paricles/s • 105-6interactions/s (1% target) • Level 1 Trigger: • Multiplicity in TOF • 104 _105central events/s • Large data rate3 GByte/s

  22. Second Level trigger flow Second Level Trigger dilepton 1:100

  23. Trigger distribution system • Trigger distribution: LVL1 (TOF Mult.) and LVL2 (MU) via CTU • DAQ synchronized via event number distribution • Total: 50 VME-Modules

  24. RICH IPU Y (pads) IPU-algorithm X correlation Hits found by the IPU and not by the algorithm X (pads) X IPU (pads) 0.2% Hits found by the algorithm and not by the IPU 0.2% X ALGO (pads) 1 ring search mask (13x13 pads) • Pattern reconstruction (96x96 pad plane) • Ring recognition • fixed 80 pads mask (ring/veto region) • local maximum search uncorrelated emulation rings Data: Nov01C-C 1.5 AGeV full field • Discrepancy: 0.4%

  25. Matching Unit Trigger condition % evts evt >= 1 ring 10.5% evt >= 1 lepton 2.9% evt >= 2 rings 4.6% evt >= 2 leptons 1.7% evt >= 1 dilepton 0.3% Preliminary Data: Nov01C-C 1.5 AGeV magnetic field Reference System: offline analysis leptons LVL2 conditions in the MU: • 1 hit in RICH • 1 hit in TOF • Df < 15° lepton Efficiency RICH IPU LVL2 integrated eff 85.3% 84.7% event eff 87.3% 86.6% N. fakes ele/evt0.24 0.19

  26. Outlook • HADES comes into operation(e/p/p sep., LVL2 trig., tracking) • 3 MDC layer will be completed this summer (p3% for /) • DAQ and LVL2 trigger commisioning Phase I (2002 – 2003) : (acc. proposals S200 ,S262) • Continuum below M inv < 600 MeV/c2 ; 0 Dalitz in C+C • High statistics e+,e- production in HI reactions C+ C @ 1 – 2 AGeV(compare to DLS) • e+e- production in p- p p- p @ 0.8 – 1.3 GeV/c(below and above threshold for r/w • e+e- pair acceptances pp  pph pp e+e-

  27. e+e- pairs in C + C collisions 25000 e+e- Ebeam = 1A GeV/c Simulation for 3 MDC setup : needs 2 * 109events ~ 5 days 89000 e+e- Ebeam = 2A GeV/c

  28. e+e- pairs in -+p reactions Pbeam = 0.8 GeV/c Simulation for 3 MDCsetup : 7 days of p- beam @ 1 * 106 s-1 !! Pbeam = 1.3 GeV/c

  29. Collaboration • Bratislava (SAS, PI) • Catania (INFN - LNS) • Clermont-Ferrand (Univ.) • Cracow (Univ.) • Darmstadt (GSI) • Dresden (FZR) • Dubna (JINR) • Frankfurt (Univ.) • Giessen (Univ.) • Milano (INFN, Univ.) • Moscow (ITEP, MEPhI, RAS) • Munich (Tech. Univ.) • Nicosia (Univ.) • Orsay (IPN) • Rez (CAS, NPI) • Sant. de Compostela (Univ.) • Valencia (Univ.)

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