The HADES experiment @GSI Collaboration: 18 Inst. 125 members - PowerPoint PPT Presentation

The HADES experiment @GSI Collaboration: 18 Inst. 125 members •Mot ivat ion •Det ect or descript ion •Perf ormance •out look

Motivation � Properties of hadrons in strong int. matter: M, Γ vs ρ , µ B , T, V Vector meson ρ , ω , φ spectral functions measurements � Hadron’s structure: VDM, Form factors, vector meson-nucleon inter. Dalitz and two-body decays, pN, π N reactions SIS / GSI : heavy ion, proton,pion beams 0 ≤ ρ ≤ 3 ρ 0 0 ≤ T ≤ 80 MeV HADES: systematic dielpton spectroscopy • meson prod. in π p / pp : ρ = 0 , T = 0 MeV • meson prod. in π A / pA : ρ = ρ 0 , T = 0 MeV • meson prod. in AA : ρ = 1−3ρ 0 , T = 80 MeV

High Acceptance DiElectron DiElectron Spectrometer Spectrometer High Acceptance Magnet SC. toroid ( 6 coils) 18 ο < ϑ < 85 ο 2π in φ Lepton Identification RICH C 4 F 10 + gas Phot. Det. CsI - cathode META TOF scintillator wall + Pre-Shower detector p/ π identification META and tracking Tracking p – measurement, vertex reconstruction MDC Drift chambers δ x ~ 80 µ m ( σ )

HADES ADES @GSI @GSI H PreShower RICH Magnet RICH +MDC I Coils Back view

HADES S. C. Magnet Magnet I LSE HADES S. C. I LSE � SC Toroid I max = 3465 A � B max = 3.7 T coil � B max = 0.7 T air ∆ p ( θ =25°) = 103 MeV/c ∆ p ( θ =80°) = 60 MeV/c � Beam operation � I = 2500 A ∆ p (25°) = 74 MeV/c

Ring I maging CHerenkov CHerenkov Detector Detector Ring I maging - - e + + e e - - identification identification e • Cherenkov light cos θ c = 1/ ß . n( λ ) . 1/ γ t ( l rad = 40 cm ) . l rad 2 N = N 0 2 0 ° � N 0 det. characteristics • Radiator (hadron blind!) 4 0 0 3 ∼ γ had < γ t < γ lep 1 1 5 4 1 C 4 F 10 : γ t = 18.3 8 3 5 5 0 0 0 0 p π > 3 GeV/c • VUV - Mirror x/X < 2% Poly-C substr. (2 mm) Al + MgF 2 coating R > 80% • Photon detector (MWPC) CsI - cath . CaF 2 window

RI CH in parts in parts RI CH Photon detector with CaF2 window & CFK radiator shell

RI CH rings RI CH rings γ e + π 0 Θ ~ 2.2 0 Strong sources e - Dalitz lead to large γ comb. backgr.!!! e + Θ ~ 0.7 0 e - Conversion

Multiwire Drif t Chambers Multiwire Drif t Chambers 0.7 % mass resolution in the ρ/ω - region • • Combinatorial background reduction – e+,e- close pair rejection

Multiwire Drif t Chambers Multiwire Drif t Chambers I PN Orsay � 4 layer/sector. � total 33 m 3 active area, 27000 cells � ∆ y<100 µ m plane resolution LHE Dubna � He-iC 4 H 10 [60-40] FZR gas mixture and low Z material GSI GSI plane ORSAY plane MDC: participating Institutions : I: GSI, II: LHE/JINR Dubna, III: FZ Rossendorf, IV: IPN Orsay

MDC module MDC module Relative Contributions in the Module x/X 0 ≈ 5 10 -4 quencher field noble gas 16% 12% 1% cover 2% window cathode 15% 35% sense 19% Cell characteristic Drift [ µ m/ns] V 50 40 30 20 10 Layer Width/m Height Area[m^2] I 76,7 75,5 0,34 [mm] II 90,5 88,3 0,49 III 180,5 178,0 1,88 [mm] IV 222,4 219,9 2,83 6 [mm]

Perf ormance of MDC MDC Perf ormance of Intrinsic spatial resolution : Proton beam, silicon tracker Layer efficiency: “In-beam” (C+C 1.8 AGeV) > 98% Spatial Resolution (microns) Orsay GSI Dubn a FZR Chamber Number

MDC Read Read- - out out MDC Daughterboards ASD8 LVL1-connector FPC- connector TDC Motherboard TDC Features : (8 channels per chip) Analog Read-out: � Differential amplifier, ASD8 chip, 8 channels, • 8 channels per chip � 1 fC intr. Noise, 30 mW/channel • 250/500 ps/channel � adjustable threshold (one for 16 channels) • “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!

TOF Θ >45 0 TOF Ch. p. distribution for C+C @ 1.5 AGeV Outer TOF wall Θ >45 0 : � 6 * 64 scint. Installed. � T line fully operational δ t : 90 – 140 ps � dE/dx measurement � tracking J. Friese, TU München

TOF- - hadron identif ication hadron identif ication TOF Preliminary TOF p [MeV/ c] counts β Mass [MeV/ c 2 ] Deuteron peak: Tof [ns] deuterons count s m 0 = 1890 MeV σ m = 551 MeV protons Mass [MeV/ c 2 ] Energy loss [MeV]

TOF- - RI CH RI CH lepton identif ication lepton identif ication TOF TOF 12500 Start-Stop 10000 inclusive tof spectrum tof resolution 7500 5000 2500 0 Exclusive tof spectrum for particles producing a 200 tof for leptons σ tof = 0.18 ns signal on the RICH in the 150 TOF-RICH coincidence ∆θ |<2° angular window | 100 and | ∆φ |<1°. 50 0 0 5 10 15 20 25 30 tof [ns]

Pre- Shower/ TOF system Θ <45 0 ε e single ≈ 80% Pre-Shower Pre-conv Post1-conv Post2-conv. Pads TOFINO � tof measurement Field δ t ≈ 0.35 ns Sense wires 2 radiation lengths Pb converter target Pre-Shower detector side view beam � 3 pad chambers (20000 pads) � em. showers in Pb converters

C+C 1.5 AGeV One event: detector response Pre-converter Post1-converter Post2-Converter e - beam p beam Shower Pre-Conv Pre-Conv Post1-Conv candidate Post1-Conv

RI CH- MDC- META lepton identif ication Dat a: Nov01 preliminary C-C 2.0 AGeV magnet ic f ield q* moment um Log z! t of [ns] t of [ns] q*moment um

RI CH- MDC- META lepton identif ication preliminary Dat a: Nov01 C-C 2.0 AGeV magnet ic f ield B = sim ( ) 2 . 4 % � Full HADES simulat ion S exp = B and dat a analysis ( ) 2 % S � RQMD ev.generat or simul. N e / N π + ∆Φ RI CH-Track(MDC-META) � RI CH & f ast t of &shower e- e+ � MDC I / I I (inner ) q* moment um [e*MeV/ c]

HADES Trigger System • Needs level 2 trigger: • Needs level 2 trigger: – Ring recognition in RICH – Ring recognition in RICH • 10 7- 10 8 paricles/s – Hit finding and tof calculation in – Hit finding and tof calculation in • 10 5-6 interactions/s (1% target) TOF TOF – El. Shower search in Pre-Shower – El. Shower search in Pre-Shower • Level 1 Trigger: – Multiplicity in TOF RICH and META candidate matching RICH and META candidate matching – 10 4 _ 10 5 central events/s via azimuthal correlations via azimuthal correlations • Large data rate – Selection of e + e - -pairs (momentum – Selection of e + e - -pairs (momentum 3 GByte/s and invariant mass analysis) and invariant mass analysis) – High rates (10 5 Hz) – High rates (10 5 Hz) – 10 µ s max. LVL2 trigger decision – 10 µ s max. LVL2 trigger decision time) time) – Parallel- und Pipeline architecture – Parallel- und Pipeline architecture FPGAs, CPLDs and DSPs FPGAs, CPLDs and DSPs

Second Level trigger f low Second Second Level Trigger Level Trigger dilepton dilepton 1:100 1:100

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

1 ring search mask (13x13 pads) RI CH I PU • Pat t ern reconst ruct ion (96x96 pad plane) • Ring recognit ion • f ixed 80 pads mask ( ring/ vet o region) • local maximum search I PU-algorit hm X correlat ion Hits found by the IPU X IPU (pads) and not by the algorithm 0.2% uncorrelat ed emulat ion rings Hits found by the Y (pads) algorithm and not by the IPU 0.2% X ALGO (pads) Dat a: Nov01 • Discrepancy: 0.4% C-C 1.5 AGeV f ull f ield X (pads)

Preliminary Matching Unit Dat a: Nov01 C-C 1.5 AGeV magnet ic f ield Ref erence Syst em: of f line analysis lept ons LVL2 condit ions in t he MU: • 1 hit in RI CH lept on • 1 hit in TOF ∆φ < • 15° Trigger condition % evts Ef f iciency evt >= 1 ring 10. 5% RI CH I PU LVL2 RI CH I PU LVL2 evt >= 1 lepton 2. 9% int egrat ed ef f 85.3% 84.7% int egrat ed ef f 85.3% 84.7% evt >= 2 rings 4. 6% event ef f 87.3% 86.6% event ef f 87.3% 86.6% evt >= 2 leptons 1. 7% N. f akes ele/ evt 0.24 0.19 N. f akes ele/ evt 0.24 0.19 evt >= 1 dilepton 0. 3%

Outlook •HADES comes int o operat ion(e/ π/ p sep., LVL2 t rig., t racking) •3 MDC layer will be complet ed t his summer ( δ p ≈ 3% f or ρ / ω ) •DAQ and LVL2 t rigger commisioning Phase I (2002 – 2003) : (acc. proposals S200 ,S262) •Continuum below M inv < 600 MeV/c 2 ; π 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 π - p π - p @ 0.8 – 1.3 GeV/c (below and above threshold for ρ/ω • e + e - pair acceptances pp → pp η → pp e + e -

e + e - pairs in C + C collisions 25000 e + e - E beam = 1A GeV/c Simulation for 3 MDC setup : needs 2 * 10 9 events 89000 e + e - ~ 5 days E beam = 2A GeV/c

e + e - pairs in π - +p reactions P beam = 0.8 GeV/c Simulation for 3 MDC setup : 7 days of π − beam @ 1 * 10 6 s −1 !! P beam = 1.3 GeV/c