Schwerionen- und Hadronenphysik an und Claudia Höhne, GSI Darmstadt KHuK Jahrestagung, 25./26.10.2007, GSI Darmstadt Einleitung GSIFOPI & HADES FAIRHADES

Schwerionen- und

Hadronenphysik an

und

Claudia Höhne, GSI Darmstadt

KHuK Jahrestagung, 25./26.10.2007, GSI Darmstadt

• Einleitung

• GSI FOPI & HADES

• FAIR HADES & CBM

• Zusammenfassung & Ausblick

2 Claudia Höhne KHuK Jahrestagung, 2007, GSI

The QCD phase diagramaim of heavy ion physics

• explore the QCD phase diagram!• study hadronic properties at high baryon densities• chiral symmetry restoration?

FOPI & HADES @GSI

A+A collisions at < 2 GeV/nucleon

HADES@FAIR

A+A collisions at 2-10 GeV/nucleon

CBM@FAIR

A+A collisions at 10 – 45 GeV/nucleon

[A

nd

ron

ic e

t a

l. N

ucl

. P

hys

. A

77

2,

16

7 (

20

06

).


The SIS18 heavy ion regime

10 20 30

t [fm/c]

≈ 10 fm/c

Probing nuclear matter at “moderate" baryon density and temperature

A long life time of the dense system (up tp 10 fm/c)

The all-dominant presence of baryonic resonances

(“resonance matter”), N/Apart ≈ 10%

The sub-threshold production of Kaons and Vector Mesons: Multi-step processes confined to the dense phase


Kaons in medium

Modified properties of hadrons in dense baryonic matter?→ mass, width, phase-space and angular distributions

in-medium kaon energy↔ equation of state in dense matter?

attractive K- N potential

repulsive K+ N potential

(yellow area: envelope of several microscopic calculations: all predict the same trend !)


FOPI – strangeness @ SIS

• Motivationhadronic properties in dense medium (1-3 0)?strangeness! (production close to threshold)→ sensitive probe!

• Kaons in mediumyields, phase space distributions, flow

• Strange Resonances Baryons! Excited hyperon *(1385)→ total strangeness, thermalisation?

• Exotica – kaonic bound states

IPNE Bucharest, Romania ITEP Moscow, RussiaCRIP/KFKI Budapest, Hungary Kurchatov Institute Moscow, RussiaLPC Clermont-Ferrand, France Korea University, Seoul, KoreaGSI Darmstadt, Germany IReS Strasbourg, France + IMP Lanzhou, ChinaFZ Rossendorf, Germany Univ. of Heidelberg, Germany + SMI Vienna, AustriaUniv. of Warsaw, Poland RBI Zagreb, Croatia + TUM, Munich, Germany


Kaon – flow measurements

directed flow:

elliptic flow:

Sensitivity of collective flow to depth of kaon potential → U(K+) = + 20 MeV,

For K- no consistent description yet by transport models: HSD ↔ IQMD

Y.J.Kim (FOPI) Ni+Ni @ 1.93 AGeV


Strange resonances* (

13

85

) s

ub

thre

sh

old

pro

du

cti

on

, X

. Lop

ez e

t al.

(FO

PI

coll

abor

atio

n), s

ubm

itte

d to

PR

L (

2007

)

• for investigation of total strangeness production baryons (!) are important!

→ test thermalization/ chemical equlibrium with statistical model

• short lived resonances (e.g. *) are expected to be also sensitive to dense medium!

• due to short lifetime * should probe finite density!

• Broadening of the width not yet observed (needs more statistics)

* in-medium:

Γ = 76 MeV at ρ = ρ0

Mean mass: attractive potential ≈ - 45 MeV at ρ0

* + (88 2%) = 39.4 MeV c = 5 fm


FOPI TOF upgrade completed!

FOPI – RPC detector: 4500 electronic channels, 6m2 active area


Online performance from 1. experiment (Sep.2007)

K+ - identification by momentum – TOF analysis up to plab=1GeV/c

System time resolution estimate from fast pions: t = 100 ps

P (

GeV

/c)

v (cm/ns)t = tmeas – ttracking (ns)

p>0.5GeV/c

+

-

K+

p


Summary of FOPI physics program (2008 – 2010)

2008 (S338): Heavy ion reactions

Ru + Ru @ 1.7 AGeV, 4 weeks Strange resonance production

Ni + Pb @ 2 AGeV, 2 weeks and flow K- - potential

2009 (S339): Pion induced reactions

+ LH2, C, Pb @ 1.7 GeV/c, 2 weeks Strangeness production

K- - potential at = 0

2010 (S349): Proton induced reactions

p + p @ 3 GeV, 2 weeks Search for ppK- - bound state

(accepted proposals by G-PAC)


In-medium properties of hadrons (electromagnetic-probes)

[Rapp, Wambach, Adv. Nucl. Phys. 25 (2000) 1, hep-ph/9909229]

• -meson couples to the medium, direct radiation from the early phase

• vector-meson dominance!

• vacuum lifetime 0 = 1.3 fm/c → dileptons = penetrating probe

• connection to chiral symmetry restoration?

pn

++

p

e+, μ+

e-, μ-

-meson spectral function


HADES

High Acceptance DiElectron Spectrometer

– Focus on the spectroscopy of vector mesons ()

– Consistent picture in pp, pA, A and AA reactions

– Supplemented by hadron spectroscopy, incl. K0

s, ,

Spectrometer with a …

– High geometric acceptance & invariant mass resolution

– High background rejection & rate capability, dedicated LVL2 trigger

Instrumental challenge!

→ e+e- rare probe:

1 e+e- decay from vector mesons per 1-10 Million reactions!

– Large background from conversion and 0-Dalitz decay


preliminary

Dileptons from C+C• excess of dilepton yield above cocktail!

• relative excess for 1 GeV/nucleon is larger than for 2 GeV/nucleon shape of relative excess similar

"cocktail A" = 0 + + (long lived)

[HA

DE

S,

PR

L 98

, 05

2301

(20

07)

]


• Quantitative analysis: deduce the absolute excess yield Yexc (beyond η), making use of the TAPS η data:

C + C 2 AGeV Phys. Rev. Lett. 98, 052302 (2007)

Yexc(2.0)/Yexc(1.0) = 2.3

± 0.6(stat) ± 1.0(sys)

Dileptons from C+C (II)

preliminary

• HADES confirms DLS!• excess (beyond η) scales like pions

→ importance of resonances!• discussions ongoing


Comparison to DLS

DLS data (C+C, 1AGeV) confirmed by HADES!

preliminary

DLS Data:

R.J. Porter et al.: PRL 79(97)1229

• extrapolation of HADES data to DLS acceptance

• theory is challenged to explain data!


Comparison HSD - HADES

• comparison of HADES data to HSD (new version including new isospin dependent Bremsstrahlung)

• lively discussions ongoing!

→ compare to p+p and p+n data!

[E. Bratkovskaya, priv. comm.]

HADES strategy:

• establish experimental "cocktail" of long and short lived e+e- pairs from pp and pn data

(s<sthres for production)

• study exclusive channels (e.g. +) in pp by missing mass spectroscopy


100% statistic analyzed :38877 signal pairs, 607 for M>150 MeV/c2

50% statistic analyzed:37800 signal pairs, 1230 for M>150 MeV/c2

Online spectrum (data from May 2007 )Preliminary not efficiency corrected spectrum

preliminary

preliminary

p+p, d+pe+e- X, 1.25 GeV


HADES schedule

Physics Runs in…

p, d, - induced A + A Status/Comment

2002 C + C 2 AGeV Published! (PRL)

2004 C + C 1 AGeV Analysis finished

2004 p + p 2.2 GeV Analysis finished

2005 Ar + KCl 1,75 AGeV Analysis ongoing

2006 p + p 1.25 GeV Analysis ongoing

2007 p + p 3.5 GeV

d + p 1.25 AGeV

… online results!

2008 p + A 3.5 GeV

2008/9 Upgrade RPC, DAQ

> 2008 + N, A Ni + Ni

Au + Au

planned

> 2014 Hades goes FAIR (8 AGeV)

"DLS puzzle"

elementary reactions!exclusive channels-beam!

chiral symmetry restoration for =0 in controled system

heavy systems!


HADES upgrade for heavier systems

• RPC (TOF with higher granularity, 80ps time resolution)

• DAQ (LVL1 rates beyond 30 KHz)

HADES at FAIR


High density matter at FAIR

[Bra

tkov

skay

a et

al.,

PR

C 6

9 (2

004)

054

907

]

UrQMD calculation of T, B as function of reaction time

(open symbols – nonequilibrium,

full symbols – appr. pressure equilibrium)

CBM • rare probes! (charm, dileptons) sensitive to medium• ... and bulk properties• aim for microscopic understanding

• higher energies (2-45 GeV/nucleon) → higher baryon densities, temperatures, energy densities created; but still over time span of 5-10 fm/c

• discovery potential: 1st order deconfinement phase transition? critical point? chiral phase transition?


Charm production at threshold

[W. Cassing et al., Nucl. Phys. A 691 (2001) 753]

HSD simulations

• CBM will measure charm production at threshold

→ after primordial production, the survival and momentum of the charm quarks depends on the interactions with the dense and hot medium!

→ direct probe of the medium!

• do c and c quarks behave differently in baryon-rich matter?

• charmonium (cc) in hot and dense matter?

• relation to deconfinement?


CBM: Physics topics and Observables

Onset of chiral symmetry restoration at high B

• in-medium modifications of hadrons (,, e+e-(μ+μ-), D)

Deconfinement phase transition at high B • excitation function and flow of strangeness (K, , , , )• excitation function and flow of charm (J/ψ, ψ', D0, D, c)• charmonium suppression, sequential for J/ψ and ψ' ?

The equation-of-state at high B

• collective flow of identified hadrons• particle production at threshold energies (open charm)

QCD critical endpoint• excitation function of event-by-event fluctuations (K/π,...)

• mostly new measurements• CBM Physics Book (theory) in preparation


CBM collaborationRussia:IHEP ProtvinoINR TroitzkITEP MoscowKRI, St. Petersburg

China:CCNU WuhanUSTC Hefei

Croatia:

University of SplitRBI, Zagreb

Portugal: LIP Coimbra

Romania: NIPNE Bucharest

Poland:Krakow Univ.Warsaw Univ.Silesia Univ. KatowiceNucl. Phys. Inst. Krakow

LIT, JINR DubnaMEPHI MoscowObninsk State Univ.PNPI GatchinaSINP, Moscow State Univ. St. Petersburg Polytec. U.

Ukraine: Shevchenko Univ. , Kiev

Univ. MünsterFZ RossendorfGSI Darmstadt

Czech Republic:CAS, RezTechn. Univ. Prague

France: IPHC StrasbourgGermany: Univ. Heidelberg, Phys. Inst.Univ. HD, Kirchhoff Inst. Univ. FrankfurtUniv. Mannheim

Hungaria:KFKI BudapestEötvös Univ. BudapestIndia:Aligarh Muslim Univ., AligarhIOP BhubaneswarPanjab Univ., ChandigarhUniv. Rajasthan, JaipurUniv. Jammu, JammuIIT KharagpurSAHA KolkataUniv Calcutta, KolkataVECC KolkataUniv. Kashmir, SrinagarBanaras Hindu Univ., Varanasi

Korea:Korea Univ. SeoulPusan National Univ.

Norway:Univ. Bergen

Kurchatov Inst. MoscowLHE, JINR DubnaLPP, JINR Dubna

51 institutions, > 400 members

Dresden, September 2007

Cyprus: Nikosia Univ.


The CBM experiment• tracking, momentum determination, vertex reconstruction: radiation hard silicon pixel/strip detectors (STS) in a magnetic dipole field

• hadron ID: TOF (& RICH)• photons, 0, : ECAL

• electron ID: RICH & TRD suppression 104

• PSD for event characterization• high speed DAQ and trigger (up to 10 MHz int. rates) → rare probes!

• muon ID: absorber + detector layer sandwich move out absorbers for hadron runs

MVD + STS

... measuring both channels would be the best crosscheck of results we can ever do!


STS tracking – heart of CBM

Challenge: high track density 600 charged particles in 25o

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 m)

• V0 track pattern recognition

D+ → ++K- (c = 317 m)

D0 → K-+ (c = 124 m)

silicon pixel

and strip detectors

→ drives CBM layout!


STS and FEE R&D

Strip sensor development with CIS ErfurtFirst test sensor delivered spring 2007

Fast self-triggered readout chip n-XYTER in collaboration with DETNIprospect: CBM-XYTER


CbmRoot simulation framework• detector simulation (GEANT3)

• full event reconstruction: track reconstruction, add RICH, TRD and TOF info

• result from feasibility studies in the following: central Au+Au collisions at 25 AGeV beam energy (UrQMD)


Open charm production• D0 → K-+ and D0 → K+- (c= 124 m), full event reconstruction

• <D0 + D0> = 1.5 ∙ 10-4 (central Au+Au collisions, 25 AGeV)

• first pixel detector (MAPS) at 10cm

• ~53 m secondary vertex resolution

• proton identification with TOF

1012 central Au+Au collisions, 25 AGeV

25 AGeVcentral AuAu


Low mass vector mesons

invariant mass spectra

• electrons: pt > 0.2 GeV/c background dominated by physical sources (75%)

• muons: intrinsic p>1.5 GeV cut (125 cm Fe absorber), use TOF information

electrons: 200k events background 4 ∙108 events – signal 20k ev.All eAll e++ee--

Comb. bgComb. bgρρ ee++ee--

ee++ee--

φφ ee++ee--

ππ0 0 γγee++ee--

ππ00ee++ee--

ηη γγee++ee--

m = 14 MeV/c2 m = 11 MeV/c2

25 AGeVcentral AuAu


electrons: 2.4 ∙1010 events

J/ m = 38 MeV/c2

' m = 45 MeV/c2

J/ and '

invariant mass spectra

• electrons: p < 11 GeV/c, pt > 1 GeV, 1‰ interaction target (25 m Au)

• muons: 225 cm Fe absorber, no pt-cut

muons: 4 ∙108 events

J/ m = 22 MeV/c2

' m = 33 MeV/c2

25 AGeVcentral AuAu


Summary & Outlook

• succesful investigation of hadronic matter at moderate densities (1-3 0)

• data on elementary interactions and serious theoretical effort essential!

• FOPI → sensitivity of kaons to dense medium demonstrated→ quantify medium modifications for strange hadrons

→ multi-strange clusters?

• HADES → "DLS puzzle" solved→ setup completed, production phase of high quality data→ broad program (e.g. p,A, Au+Au), upgrade and move to FAIR

• investigate high baryon density region of QCD phase diagram (deconfinement phase transition, chiral symmetry restoration)

• CBM → comprehensive investigation including rare probes (dileptons and charm) → detailed simulations, R&D ongoing

• complementary effort to LHC


Backup


Vector Mesons: p+p, 3.5 GeV

May 2007May 2007, preliminary, online results! No final calibration/alignment!

Hadron analysis: missing mass Hadron analysis: missing mass techniquetechnique:

– pp 4-prong (+++-)-selection – <2% of statistics– pppp+0-

– ppppK+K-

ee++ee-- pair analysis pair analysis: not shifted! Preliminary

calibration… – Extra yield below VM pole

mass.

pp missing mass (GeV/c2)

yiel

d (

a.u

.)

η

pppp+0-

pp missing mass (GeV/c2)

Yie

l (a

.u.)

ppppK+K-

S/BS/B1010

11

0.5 1.0 0.5 1.0

MMeeee

Preliminary

Preliminary

PRELIMINARY

Documents

Schwerionen- und Hadronenphysik an und Claudia Höhne, GSI Darmstadt KHuK Jahrestagung, 25./26.10.2007, GSI Darmstadt Einleitung GSIFOPI & HADES FAIRHADES