C. Schwarz

Physics with Antiprotons - Detector -

• Detector requirements

• Overview of the detector concept

• Detector components

• Trigger

• Costs

C. Schwarz

Detector requirements (simulations)

• Energy release of charmed hadrons high → large ptrans → large angles

• High cm-velocity (fixed target) → high energies → small angles

Formation of Ψ’ and decay in muons

Ψ’→μ+μ-

Ψ’→J/Ψ + X ↓ μ+μ-

electrons similar→ calorimeter for large angles.

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Detector requirements (PID)

• Forward angles need π/K separation up to 3 GeV/c: Cherenkov n=1.02

• Backward: higher value of n.

p+p → ΦΦ→ 4K s½ =3.6 GeV

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Overview of detector concept

internal target

forward spectrometertarget spectrometer

Heavy charmed mesons decay inlight products with large pt.Solenoid is important.

top view

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Overview of detector conceptside view

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Central tracking: Microvertex Detector 7.2 mio. barrel pixels

50 x 300 μm

2 mio. forward pixels100 x 150 μm

beam pipe

pelle

t pi

pe

Space resol.: σz=80μm, σ r-φ=15μmTrack resol. : σL=60-300 μm σT =12μm

Readout: ASICs (ATLAS/CMS) 0.37% X0

or pixel one side – readout other side (TESLA)

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Central tracking:

Straw tubesWASA@Celsius

15 skewed double layers to remove left-right ambiguity

Ø 4-8 mm

skew angle: 5-15o APUD@HESR

p+p → φ φ →K+ K- K+ K-

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Mini Drift Chambers• 6 layers of sense wires in 3 double

layers (y,u,v)

• not stretched radially (mass)

• realized at HADES• expected counting rates

• position resolution 70μm

HADES@GSI

APUD@HESR

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Particle identification• PID from

• 00<Θ<50 hadronic calorimeter

• 50<Θ<220 Aerogel Cherenkov Counters

• 220<Θ<1400 DIRC (BABAR@SLAC)

DIRC thickness: 0.19 X0

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Cherenkov opening angle: Internal reflection → different vel. thresholds

p + p → J/Ψ+φ @ 8.5AGeV/cε=80%

PID: DIRC

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Calorimeter

PbWO4

Length = 17 X0

APD readout (in field)σ(E) = 1.54% / E½ + 0.3%

pp J/Ψ + η γγ

140o

5o

22o

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e±/π± sep.

electron/pion separation 10-3

2 4 6 8 p (GeV/c)0

Ed

ep (

GeV

/c)

2

4

6

8

10

e+/-

π+

2 4 6 8 p (GeV/c)0

10-3

π+ probability

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Trigger• Front end and DAQ structure

• pipelining

• 3-level trigger

• Ex.: HADES/LHCb

• LVL-1: <106 events/s• J/ψ large pT (e, μ)

• neutral K, hyperons: multiplicity jump in MVD

• D-meson: vertex

• LVL-2: <104 events/s• Pattern recognition

• EMC: em. shower photon reconstruction

• Minv from EMC or muons

• LVL-3: <103 event/s• global kin. conditions

HADES@GSI

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Pellet target

• Frozen hydrogen pellets 20-40μm

• Δx=±1 mm (±0.04o)

• 60 m/s

• 70000 pellets/sec.

• 1014-1016 atoms/cm2 (avg.)

1 mm

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CostsSolenoid 2.5 M€

Calorimeter (target spectrometer) 12.5 M€

Tracking (pixel detector, straw tubes) 3.0 M€

Cherenkov 3.5 M€

Hypernuclei (read out electronics,micro tracker) 2.0 M€

Varia (e.g. refurbishing of forward detector parts) 1.9 M€

Trigger 1.5 M€

Infrastructure 2.0 M€

Contingency 2.0 M€

Sum 30.9 M€