Equation of State Study in UU collisions at CSR, Lanzhou

Quark Matter 2006

Nov14-20 Shanghai, China

Z. G. XiaoInstitute of Modern Physics, CAS, Lanzhou, China

Collaborators:X. Dong2, F. Liu3, X.F. Luo2, K.J. Wu3, H. S. Xu1, N. Xu4

1 Institute of Modern Physics2 University of Science and Technology of China3 Central China Normal University4 Lawrence Berkeley National Laboratory

Contents

1 Introduction: EOS interest 2 HIRFL-CSR* complex

2.1 Machine status2.2 Experiment: status & plan

3 UU collision simulations3.1 High density in UU3.2 Event selection

4 Summary

HIRFL: Heavy Ion Research Facility at Lanzhou

CSR : Cool Storage Ring (500~1000MeV/u for HI )

EOS and its general interest EOS used as input, tested by exp./model. consistency.

Nucl. EOS

Initial conditions

Star fate, …

M-R

Max. M.Const.

… …

Evolution dynamicsCompact Star:

Initial conditions

Freeze

Out

Flow

K, …

Cluster

GMR …

Transport Process

H I C:

EOS representation

T. Klaehn et al., Phys. Rev. C 74, 035802 (2006)

00sym

20sym

20 )()()()(),( EEEEE

...

3...

1621823

22 L

JaV

Esym

Key Issues for EoS Program

1 Identify the bulk-matter with partonic degrees of freedom

2 Study the properties of the partonic matter

3 Demonstrate the transition between partonic and hadronic worlds

4 Understand multi-facets of HIC relevant to EOS study

CSR

1 Introduction: EOS interest 2 HIRFL-CSR* complex

2.1 Machine status2.2 Experiment: status & plan

3 UU collision simulations3.1 High density in UU3.2 Event selection

4 Summary

HIRFL-CSRcomplex

ECR Ion Source SFC k=70 (few AMeV) SSC k=450(~100 AMeV) CSRm Cooler synch.

~12.6Tm

~2.8GeV proton CSRe Acc./Deccel.

~9.6Tm RIBLL2 R~1200

ITE

ETE

J. W. Xia et al., NIM A 488, (2002) 11

Commission: 2006~2007

CSR Performance

CSRm CSRe

Ion species proton, C-U p, C-U,RIB,HCI

Beam Energy

(MeV/u)

Bmax=1.6T

2.8GeV p

1.1GeV/u 12C6+

0.52GeV/u 238U72+

2.3GeV p

~1 GeV/u 12C6+

~ 0.5 GeV/u 238U72+

P/P <10 － 4 <10 － 5

P/P 0.15% 0.5%

Emittance 5 mm mrad 1 mm mrad

7→1000MeV/u (C6+) Ramping Test 06/10/15 22:45

H = 2→1, frf = 0.45→1.63MHz, G = 11.3Tm

Particles: 2x108

External Target Facility (I)

Neutron + LCP + First experiment shifted to 2007

Conceptual Layout of ETF (II)

• 4 times larger acceptance of Dipole + Tracking inside;

• Gamma ball made of CSI;

• TOF (mRPC) covers forward region (30o).

Five years of construction after approved

NW: Prototype test/simulation results

Simulation

Real Test

Scintillator : <80

Calorimeter: <100

1 Introduction: EOS interest 2 HIRFL-CSR* complex

2.1 Machine status2.2 Experiment: status & plan

3 UU collision simulations3.1 High density in UU3.2 Event selection

4 Summary

Advantageous UU collisions

δ=0.23, A=238

Deformation larger volume along z axis

Good for collision dynamics studies

? Experimental observation

? Event selection

Tip-TipBody-Body

Density achieved in UU UU > AuAu at both energies 20AGeV: Tip-tip > Body-Body

520AMeV: Tip-tip ~ Body-Body

High energy

Low energy

B. A. Li et al., PRC61(2000), 021903

Idea of the event selections

At b=0

Tip-TipBody-Body

v2 = 0 v2 ≠ 0- high density!- longer duration!- easier reach thermalization!

Event selection in UU

Body-Body collisions exhibit large anisotropy in azimuth.

Event selection in UU

Event selection:

1) neutron multiplicity cut suppress body-body events

2) Larger ratio of tip-tip collisions survives a additional v2 cut.

3) Random geometrical configuration to be simulated.

5 Summary

EOS studies are drawing much attention and calling for more systematic studies.

HIRFL-CSR at Lanzhou, China can hope to add opportunities for nuclear EOS study in the high net-baryon density region. An External Target Facility (ETF) is in the preparing stage and detector R&D has started.

UU collisions provide a unique opportunity for creating a system with extended energy density and duration. The advantage is maintained only by effective identification of the geometrical configuration. Correlation between v2 and forward neutron multiplicity might practically help in the relevant energy region.

BACKUP SLIDES START HERE

Phase Space at 400MeV/u symmetrical collisions

BUU calculations

QCD Phase Diagram

CSR

EOS from HIC

DF favors softer EOS, while EF favors harder one; K roughly constrained in (167, 380)

P. Danielewicz et al., Science, 298(2002), 1592

Puzzles found more in detailed investigatioPuzzles found more in detailed investigationnMore in A. Andronic et al., PRC67(2003), 034907; PLB612(2005), 173

C. Fuchs et al., Phys. Rev. Lett 86, 1974 (2001)

Complication arises (1): Finite size effect

Due to nuclear transparency, density and/or pressure achieved in HIC is not so high as the full stopped scenario predicts. reduce the sensitivity on EOS ? virtually “soften” EOS ?

W. Reisdorf et al., PRL92(2004), 232301

CSR range

Esym and its density dependence

Probes: Mesons: pion ratio, Kaon rat

io n/p differential flow, ratio n/p ratio of fast nucleons Isospin diffusion IMF isospin HBT correlation function ……

00symsym )()( EE

CSR range

Esym: Isospin diffusion 124Sn+112Sn

Ein= 50MeV/u

69.0

0sym 6.31)(

E

B. A. Li et al., PRC 72, 064611 (2005)

L. W. Chen et al., PRL 94, 032701(2005)

M. B. Tsang et al., PRL92, 062701(2005)

Esym: n/p flow n/p flow predicted different, while experimentall

y NOT observed!

BUU model

Aladin+FOPI

Why ???

B. A. Li, PRL88 (2001), 192701

Y. Leifels et al., PRL71(1993),963

Au+Au 400MeV/u

Neutron Wall

Active area 1.5×1.5m2

Thickness 1m

Acceptance ±3.80

coverage 11~20 mSr

Angular resolution 0.30

Efficiency （ 1 GeV n ） >90%

Position resolution ±8cm

E resolution （ < 1 GeV n ）

5 %

Main parameters

Big Dipole ready

Main parameters

B Field 1.6 Tesla

Gap height 270 mm

Gap Width 1000 mm

Thickness 980 mm

Distance to target 1 m

MWDC before and after dipole