Carsten Schwarz12.12.01 KP2 Physics with anti protons at the future GSI facility Physics program...

Carsten Schwarz 12.12.01 KP2

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


Physics programCharmoniumspectroscopy

Medium modificationsof D mesons and J/Ψ in nuclei

Hypernuclei CP violation

GlueballsHybrids


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


Medium modifications

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

Look eg. for decay ofΨ’ DD


• 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-


Charmonium spectroscopy

high resolution helps to identifystates


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


Glueball, Hybrids


Hypernuclei

-

3 GeV/c

K+KTrigger

_

secondary target

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

study of interaction

p


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


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.


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


HESR-detector

Internal target

forward spectrometertarget spectrometer

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

top view


HESR detectorside view


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)


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


TS momentum resolution (Geant 4)

MVDstraw tubesMDC

pp(s = 4.4 GeV/c2) J/

σM=1.2% ???


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


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

DIRC PID

B = 2 Tesla:Azimuthal deflection →

more homogeneous detection efficiency


DIRC PID (Geant4)

p p(s = 3.6 GeV/c2)

misidentification of π as K

K efficiency

PID+tracking


Calorimeter

PbWO4

Length = 17 X0

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

pp J/Ψ + η γγ

140o

5o

22o


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


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


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€


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

Carsten Schwarz12.12.01 KP2 Physics with anti protons at the future GSI facility Physics program...

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