STORI’02Carsten Schwarz Physics with p at the Future GSI Facility Physics program Detector set-up...

STORI’02 Carsten Schwarz

Physics with p at the Future GSI Facility

• Physics program

• Detector set-up p

e- cooler detector

High Energy Storage RingHESR

High luminosity modePmax = 1.5-15 GeV/cLmax < 2·1032 cm-2 s-1

Δ p/p ~ 10-4 (stochastic cooling)

High resolution modePmax = 1.5-8 GeV/cLmax 1031 cm-2 s-1

Δ p/p ~ 10-5 (electron cooling)


Physics program

Charmoniumspectroscopy

Medium modificationsof D mesons and J/Ψ in nuclei

HypernucleiCP violation

GlueballsHybrids


James Ritman Univ. Giessen


• Charmonium gives information about QCD confinement potential.

• Many states are still missing.

• pp: direct formation of all states.

• HESR allows investigation of states above DD threshold.

• Cooled beams with Δp/p=10-4…10-5 allow high precision scan of resonances.


40 keV

Crystal Balle+e-



Crystal Balle+e-


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


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


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:

Experiment: 1010 reconstructed ΛΛ

L=2·1032 cm-2 s-1 → >1 year running

5-4- 10 ... 10

A


Angular acceptanceFormation of Ψ’ and decay in myons

Ψ’→μ+μ-

Ψ’→J/Ψ + X ↓ μ+μ-

electrons similar→ calorimeter for large angles.


HESR Detector

Internal target

forward spectrometertarget spectrometer

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

top view


Particle identification

• 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


Tracking, Micro Vertex Detector 7.2 mio. barrel pixels

50 x 300 μm

2 mio. forward pixels100 x 150 μm

beam pipepe

llet

pipe

Readout: ASICs (ATLAS/CMS) 0.37% X0

or pixel one side – readout other side (TESLA)


MVD, single track resolution

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


Target spectrometer, momentum resolution

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


Particle identification

pp(s = 4.4 GeV/c2) J/


Calorimeter

PbWO4

Length = 17 X0

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

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

STORI’02Carsten Schwarz Physics with p at the Future GSI Facility Physics program Detector set-up...

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