Status of the CBM experiment Claudia Höhne, GSI Darmstadt
Features of the the phase phase diagramme diagramme Features of QCD inspired effective models predict rich structure of the phase diagramme at finite µ B . � Substantial depletion of the ciral condesate over almost the full lifetime of the fireball. � Separation of the chiral from the deconfinement phase transition. � 1st-order transition with a critical end point Quark-Gluon Plasma Cross over transition? Critical point? 1 s t o AGS t r r a d n e s r < > i q q t i o µ T , n B ? < > q q = µ = T 0 , 0 SIS B Hadron Gas Hadron gas Nuclei Bernd- Bernd -Jochen Jochen Schaefer, Jan M. Schaefer, Jan M. Pawlowski Pawlowski, , Jochen Jochen Wambach, , priv priv. comm. and Phys. Rev. D. 76 074023 . comm. and Phys. Rev. D. 76 074023 Wambach 2
The Physics Program of CBM in total The Physics Program of CBM in total Deconfinement phase transition at high ρ B • Excitation functions of bulk � excitation function and flow and rare observables! of strangeness (K, Λ , Σ , Ξ , Ω ) • Bulk observables with � excitation function and flow excitation function and flow � “unlimited” statistics Λ c ± , , Λ of charm (J/ charm (J/ ψ ψ , , ψ ψ ', D ', D 0 , D ± ) of 0 , D c ) • Systematic studies of rare � melting of J/ melting of J/ ψ ψ and and ψ ψ ' ' � observables (charm, QCD critical endpoint dileptons) with excellent statistics � excitation function of event- -by by- -event fluctuations (K/ event fluctuations (K/ π π ,...) ,...) event The equation-of-state at high ρ B � collective flow of hadrons � particle production at threshold energies (open charm?) Onset of chiral symmetry restoration at high ρ B medium modifications of hadrons ( ρ ρ , , ω ω , , φ φ → → e+e � in in- -medium modifications of hadrons ( e+e- -( (µ µ+ +µ µ- -) ), D) , D) � 3
Experimental challenges Central Au+Au collision at 25 AGeV � up to 10 6-7 Au+Au reactions/sec 160 p 400 π - 400 π + 44 K + 13 K - � hit densities 1 – 100 (cm 2 event) –1 UrQMD + GEANT � fast and radiation hard detectors � free-streaming readout electronics � online event selection (high-level trigger) � high speed data acquisition � high precision vertex reconstruction � identification of leptons and hadrons � large, homogenous acceptance ( φ symm.) � coverage of large surfaces overall detector concept 1st round of feasibility studies Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 4
The CBM experiment • tracking, momentum determination, vertex reconstruction: radiation hard silicon pixel/strip detectors (STS) in a magnetic dipole field • hadron ID: TOF (& RICH) • PSD for event characterization • photons, π 0 , η : ECAL • high speed DAQ and trigger → rare probes! • electron ID : RICH & TRD • muon ID : absorber + detector layer sandwich → π suppression ≥ 10 4 → move out absorbers for hadron runs ECAL TOF TRD RICH absorber + STS + detectors MVD magnet Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 5
CBM hardware R&D Forward Calorimeter RICH mirror Silicon GEM microstrip detector dipole magnet MVD: Cryogenic n-XYTER FEB RPC R&D operation in vacuum Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 6
CBM feasibility studies ) 2 D 0 Entries / 8 (MeV/c • feasibility studies performed for all major 600 Eff. = 3.25% channels including event reconstruction and S/B = 4.4 2 σ semirealistic detector setup 400 0 0 52K D + 174K D 200 12 per 10 central events di-electrons di-muons ρ ω φ 1.5 2 2.5 3 9 central trigger (10 ) 2 m (GeV/c ) ) inv 2 + 12 44K Λ /10 central events Entries / 8 (MeV/c c 30 - + + Λ → pK π c Λ c 20 eff = 0.18% ρ ω φ S/B = 1.9 10 0 2 2.5 3 2 m (GeV/c ) J/ ψ inv J/ ψ 3 10 ψ ' 2 10 ψ ' 10 1 Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 7 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 2 M , GeV/c inv
Outline • overall detector concept � • 1st round of feasibility studies � Feasibility studies detector R&D detector constraints -demonstrators layout optimization - prototypes requirements trigger concepts …. Data handling online event reconstruction trigger Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 8
Outline (II) Open charm MVD + STS Trigger → online track reconstruction Low-mass dileptons RICH & TRD J/ ψ , ψ ‘ MuCh Particle ratio fluctuations RPC Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 9
STS tracking – heart of CBM Challenge: high track density: ≈ 600 charged particles in ± 25 o Task • track reconstruction: 0.1 GeV/c < p ≤ 10-12 GeV/c ∆ p/p ~ 1% (p=1 GeV/c) • primary and secondary vertex reconstruction (resolution ≤ 50 µ m) • V 0 track pattern recognition radiation hard and fast silicon pixel and strip detectors N ~ 10 -5 / event c τ = 312 µ m self triggered FEE high speed DAQ and trigger online track reconstruction! Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 10
Open charm reconstruction � STS: 8 stations double-sided Silicon micro-strip sensors (8 × 0.4% X 0 ) � MVD: 2 stations MAPS pixel sensors (0.3% X 0 , 0.5% X 0 ) at z = 5cm and 10cm � no K and π identification, proton rejection via TOF D ± → K π π , c τ = 317 µm D 0 → K π , c τ = 123 µm 10 10 centr. ev. 10 9 centr. ev. eff = 4.4% eff = 2.6% _ S/B = 6.4 (D 0 ) S/B = 2.4 (D - ) 2.1 (D 0 ) 1.1 (D + ) 10 12 minbias events: ~ 6.4k D 0 + 16k D 0 19k D + + 42k D - and Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 11
D meson reconstruction • important layout studies: MAPS position and thickness ! • HSD: <D+> = 8 · 10 -6 /ev (minbias Au+Au collisions, 25 AGeV) • D+ → K- π + π + 9.2% BR • 0.1 MHz interaction rate (MAPS readout time 10 µ s, small pile-up ok) • 10 12 minb events ~ 16 weeks running time (100% beam availability) ~10 13 n eq /cm 2 = lifetime of MAPS 1st MAPS Position of D+ D+ D+ in 10 12 ev. thickness 1st MAPS * S/B (2 σ ) efficiency 150 µ m 10 cm 4.2% 9 31·10 3 500 µ m 10 cm 1.05% 0.93 8·10 3 300 µ m 19·10 3 5 cm 2.6% 1.1 * 2nd MAPS, 500 µ m Si equivalent, 10 cm (1st 5 cm) or 20 cm Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 12
Micro Vertex Detecor (MVD) Development Artistic view of the MVD MAPS demonstrator! • thickness • readout speed • radiation hardness M onolithic A citive P ixel S ensors in commercial CMOS process 10 × 10 µ m 2 pixels fabricated, die thinned to 50 µ m ε > 99%, ∆ x ~ 1.5 – 2.5 µ m glued to support. IPHC, Strasbourg (M. Winter et al.) Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 13
MAPS Demonstrator @ IKF Frankfurt • all parts in house, under test or ordered • demonstrator to be completed and tested until mid 2009!! • in parallel: investigate zero suppression, setup analysis software Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 14
First in-beam experiments of Si strips! GSI: Test beam line with 2.5 GeV protons CBM pre-prototype detector systems with free-streaming read-out electronics 2 double-sided silicon microstrip detectors 2 GEM Front-end board DAQ Readout online/offline detectors with self-triggering controller analysis (FAIRroot) n-XYTER chip IHEP: SVD-2 experiment, 50 GeV protons CBM demonstrator tracking station operated in the SVD-2 beam tracker SVD-2 DAQ online/offline 1 tracking station with Readout board with analysis a double-sided silicon Gassiplex chips microstrip detector Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 15
Results from in-beam experiments correlation of fired strips spatial resolution vertical- horizontal- rms rms vertical horizontal 15.3 µ m 14.8 µ m detector hits ADC back side cluster charge cluster front-back size track residuals X [mm] track residuals Y [mm] corresponds to 50 µ m strip pitch/ √ 12 [strips] ADC front side tracking efficiency ~ 100% Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 16
R&D on radiation hard Si microstrip detectors Neutron fluence through double-sided microstrip detectors R&D activities: Silicon Tracking System • novel systematic up to 10 15 n eq /cm 2 Prototype CBM01 – focus on STS 2D/3D device and system aspects, radiation soft process simulations in 6 years of operation (ISE-TCAD/Synopsis) • irradiation tests • fall back solution: CBM02 – first prototype with radiation tolerant design radiation hard single- 90° test detectors sided detectors main detector 15° stereo angle 50 µ m strip pitch 4" wafer, 285 µ m Si Claudia Höhne Physics Symposium, 13th CBM collaboration meeting, GSI, March 2009 17
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