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Physics with anti protons at the future GSI facility

• Physics program

• Detector set-up

p

e- cooler detector

High Energy Storage RingHESR

Pmax = 15 GeV/cLmax = 2·1032 cm-2 s-1

Ø < 100 μmΔ p/p < 10-5

>> cooled anti protons>> internal target

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Physics programCharmoniumspectroscopy

Medium modificationsof D mesons and J/Ψ in nuclei

Hypernuclei CP violation

GlueballsHybrids

Carsten Schwarz 12.12.01 KP2

Medium modificationsof D mesons and J/Ψ in nuclei

Continuation of present GSI physicsFOPI, KAOS, HADES, …HESR

Signal: medium modification ofproduction threshold,resonance widthe.g. Ψ’, χ2

Absorption cross section of J/Ψ in nuclei (ρ=ρ0).

pionic atoms

KAOS/FOPI

HESR

π

K

D

vacuum nuclear mediumρ = ρ0

π+

π-

K-

K+

D+

D-

25 MeV

100 MeV

50 MeV ?

Mass modifications of mesons

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Medium modifications

Hayashigaki, Phys. Lett. B 487 (2000) 96Sibirtsev Nul. Phys. A 680 (2001) 274c

Look eg. for decay ofΨ’ DD

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• Charmonium gives information about QCD confinement potential.

• Many states are still missing.

• pp: direct population of all states.

• HESR allows investigation of states above DD threshold.

• Cooled beams with Δp/p≤10-5 allow high precision scan of resonances.

Charmoniumspectroscopy

40 keV

Crystal Balle+e-

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Charmonium spectroscopy

high resolution helps to identifystates

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GlueballsHybrids

qqg ggg

Hybrid Glueball

Normal meson: 2 fermionsP = (-1)L+1

C = (-1)L+S

Excited glue: bosonic degree of freedom→ exotic quantum numbers eg. JPC=1-+, 0--, 0+-, 2+-…→ normal quantum numbers

Signal:exotic quantum numbers:

partial wave analysisnormal quantum numbers:

model comparison (LGT)

mixing with normal mesonscharm sector: few resonances

with small widths

qq

Meson

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Glueball, Hybrids

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Hypernuclei

-

3 GeV/c

K+KTrigger

_

secondary target

-(dss) p(uud) (uds) (uds)

study of interaction

p

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CP violation in Hyperon decay

p + p → Λ +Λ ↓ ↓ pπ- pπ+

• Measure decay asymmetry of angular distribution of p relative to Λ-Hyperon momentum.

• Ip(θp) ~ 1+α cos(θp) for Λ

• Ip(θp) ~ 1+α cos(θp) for Λ

• CP conservation: α = α

• Signal for CP violation:

Theoretical prediction: ~10-4 ~ 10-5

Experiment: 1010 reconstructed ΛΛ

L=2·1032 cm-2 s-1 → >1 year running

A

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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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HESR-detector

Internal target

forward spectrometertarget spectrometer

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

top view

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HESR detectorside 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

Readout: ASICs (ATLAS/CMS) 0.37% X0

or pixel one side – readout other side (TESLA)

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MVD single track resolution (Geant 4)

σD0=51 μm σZ0=82 μm

x

y

zD0

Z0

p p 8.5 GeV

2π+ 2π-

Vertex resolution is sufficient for D-physics

c(D) = 314 μm, c(D0) = 124 μm

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TS momentum resolution (Geant 4)

MVDstraw tubesMDC

pp(s = 4.4 GeV/c2) J/

σM=1.2% ???

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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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B = 0 Tesla:Cherenkov opening angle:Internal reflection → different vel. thresholds

DIRC PID

B = 2 Tesla:Azimuthal deflection →

more homogeneous detection efficiency

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DIRC PID (Geant4)

p p(s = 3.6 GeV/c2)

misidentification of π as K

K efficiency

PID+tracking

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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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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) 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 1.9 M€

Trigger 1.5 M€

Infrastructure 2.0 M€

Contingency 2.0 M€

Sum 30.9 M€

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Collaborations: Working group:

LEAR, COSY, SATURNE community

Munich GermanyBochum “Giessen “Dresden “Erlangen “Jülich “Ferrara ItalyTurin “Krakow PolandWarsaw “

T. Barnes D. BettoniR. Calabrese M. DürenS. Ganzhur V. HejnyH. Koch U. LynenV. Metag H. OrthS. Paul K. PetersJ. Pochodzalla J. RitmanL. Schmitt C. SchwarzK. Seth W. WeiseU. Wiedner

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