Results of the ASY-EOS experiment at GSI: The symmetry energy at - - PowerPoint PPT Presentation

NSMAT2016:

Results of the ASY-EOS experiment at GSI: The symmetry energy at suprasaturation density

• W. Trautmann

GSI Helmholtzzentrum, Darmstadt, Germany

NSMAT2016:

Results of the ASY-EOS experiment at GSI: The symmetry energy at suprasaturation density

Russotto et al., PRC 94, 034608 (2016)

• W. Trautmann

GSI Helmholtzzentrum, Darmstadt, Germany

FOPI-LAND UrQMD ASY-EOS Sensitivity to density Potential for future exp.

Access to high density

Bao-An Li, PRL 88 (2002): differential flows in heavy ion reactions

central Sn+Sn

Bao-An Li, NPA 708(2002)

soft stiff soft stiff

elliptic flow/squeeze out

• 0.05

0.05 v2

Au+Au 400A MeV

0.25 < b0 < 0.45 FOPI protons asy-h

• 0.05

0.05

• 1

1 y0 v2

asy-s p n Z=1

data: Reisdorf et al., NPA 876 (2012) UrQMD: Q. Li et al., PRC 89 (2014)

0.25 < b0 < 0.45

with Plastic Ball at Bevalac: H.H. Gutbrod et al., PRC 42, 640 (1990) for neutrons with FOPI-LAND at GSI:

• Y. Leifels et al., PRL 71, 963 (1993)

asy-hard asy-soft

pressure gauge for neutron-star matter

differential squeeze-out

neutron-over-charged particle elliptic-flow ratio in neutron-rich systems analysis with transport UrQMD (Li & Bleicher) Tübingen QMD (Cozma) tested with FOPI-LAND data

197Au + 197Au @ 400 A MeV

pressure gauge for neutron-star matter

neutron-over-charged particle elliptic-flow ratio in neutron-rich systems analysis with transport

UrQMD (Li & Bleicher) Tübingen QMD (Cozma)

tested with FOPI-LAND

197Au + 197Au @ 400 A MeV

SB: shadow bar for background measurement

LAND 2 LAND 1 SB acceptance in pt vs. rapidity main yield here neutron squeeze-out:

• Y. Leifels et al., PRL 71, 963 (1993)

Forward Wall for centrality and reaction-plane

• rientation

Large Area Neutron Detector 5 m

FOPI-LAND experiment

beam

Forward Wall LAND

≈ 3 m diameter 700 plastic scintillator elements measuring energy loss and time 2x2x1m3 iron/plastic time-of-flight spectrometer 400 channels thin plastic veto-wall

FOPI-LAND experiment

azimuthal angular distributions

near target rapidity mostly directed flow at mid-rapidity strong squeeze-out near projectile rapidity mostly directed flow fitted with Fourier expansion: f(∆φ)=a0*(1.0+2v1*cos(∆φ)+2v2*cos(2∆φ)) ∆φ = φparticle – φreaction plane ratios compared to UrQMD model predictions

• Q. Li et al., J. Phys. G 31(2005); 32 (2006)

relative to the reconstructed reaction plane for neutrons, background subtracted 0 ∆φ 2π

γ=1.5 γ=0.5

neutron/hydrogen FP1: γ = 1.01 ± 0.21 FP2: γ = 0.98 ± 0.35 neutron/proton FP1: γ = 0.99 ± 0.28 FP2: γ = 0.85 ± 0.47 adopted: γ = 0.9 ± 0.4

FPx: parametrizations of N-N Xsections

small effects on ratios linear

results from FOPI/LAND experiment

γ=1.5 γ=0.5

δ = (ρn–ρp)/ρ

= 22 MeV·(ρ/ρ0)γ+12 MeV·(ρ/ρ0)2/3

linear supersoft

Fuchs and Wolter, EPJA 30 (2006)

Esym = Esym

pot+Esym kin

EA(ρ,δ) = EA(ρ,0) + Esym(ρ) ∙ δ2 + O(δ4)

the symmetry energy from nuclear many-body theory

parametrization of Esym

pot in UrQMD

Esym(ρ) ρ/ρ0 Esym

pot (MeV) (APR)

γ=1.5 γ=0.5

δ = (ρn–ρp)/ρ

= 22 MeV·(ρ/ρ0)γ+12 MeV·(ρ/ρ0)2/3

linear supersoft

Fuchs and Wolter, EPJA 30 (2006)

Esym = Esym

pot+Esym kin

EA(ρ,δ) = EA(ρ,0) + Esym(ρ) ∙ δ2 + O(δ4)

result of FOPI-LAND analysis γ = 0.9 ± 0.4

Russotto et al., PLB 697 (2011) 471

(APR)

parametrization of Esym

pot in UrQMD

Esym(ρ)

FOPI-LAND

updates and model studies: Trautmann and Wolter, IJMPE 21 (2012) Cozma et al., PRC 88, 044912 (2013) Russotto et al., EPJA (2014) 50:38

• Y. Wang et al., PRC 89, 044603 (2014)

ρ/ρ0 Esym

pot (MeV)

400A MeV

from M.D. Cozma et al., PRC 88 (2013)

Cozma et al. Russotto et al.

soft (x=1)

systematic parameter test with Tübingen QMD*)

steps towards model invariance:

tested in UrQMD: FP1 vs. FP2, i.e. momentum dep. of NNECS tested in T-QMD: soft vs. hard 190<K<280 MeV density dependence of NNECS asymmetry dependence of NNECS wave packet 2.5<L<7.0 fm2

• ptical potential

momentum dep. of isovector potential conclusion: robust observable super-soft not compatible with FOPI- LAND data statistics insufficient => ASY-EOS *) V.S. Uma Maheswari, C. Fuchs, Amand Faessler, L. Sehn, D.S. Kosov, Z. Wang, NPA 628 (1998)

Asy-Eos experiment S394 in May 2011

studied reactions:

197Au + 197Au @ 400 A MeV 96Ru + 96Ru @ 400 A MeV 96Zr + 96Zr @ 400 A MeV

CHIMERA, ALADIN Tof-wall, µ-ball, for impact parameter

• rientation and modulus

Constraining the Symmetry Energy at Supra-Saturation Densities with Measurements of Neutron and Proton Elliptic Flows Co-Spokespersons: R.C. Lemmon and P. Russotto

3,8 m

Laboratori Nazionali del Sud Catania, Sicilia 4 double rings

• f CHIMERA,

LNS Catania

spokespersons: P. Russotto (Catania) R.C. Lemmon (Daresbury) 93 authors from 14 countries

recent analysis: Yongjia Wang (Huzhou) Dan Cozma (Bukarest) 93 authors from 14 countries

0.4 − 0.2 − 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

1 10

2

10

3

10

4

10

t

β γ

lab

y

AToF CHIMERA LAND MicroBall

c.m. Proj

coverage

P . Russotto et al., PRC 94, 034608 (2016)

flow ratio vs transverse momentum

P . Russotto et al., PRC 94, 034608 (2016)

0.3 0.4 0.5 0.6 0.7 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

/A (GeV/c)

t

p

ch 2

/v

n 2

v

stiff soft 0.10 ± =0.75 γ γ=0.5 γ=1.5

L=72±13 MeV

FOPI-LAND: Russotto et al. PLB 697 (2011)

from acceptance-integrated flow ratios

P . Russotto et al., PRC 94, 034608 (2016)

"A way forward in the study of the symmetry energy ..."

Horowitz et al., JPhG 41 (2014) following NUSYM13

maximum sensitivity

• f structure data near 2/3 ρ0

Zhang and Chen (PLB 726 (2013)) use Skyrme-Hartree-Fock to analyze isotope binding energy difference and neutron skin thickness of Sn isotopes; B.A. Brown (PRL 111 (2013)) uses Skyrme, properties of doubly-magic nuclei (binding energies, rms charge radii, and single-particle energies) and ∆rnp=0.16 – 0.24 fm for 208Pb.

20 40 60 80 0.5 1 1.5 2

ρ/ρ0 Esym (MeV)

n/ch flow Brown Zhang HIC Sn+Sn IAS FOPI-LAND ASY-EOS

L=63±11 MeV

FOPI-LAND: Russotto et al. PLB 697 (2011)

with Esym(ρ0) = 31 MeV

P . Russotto et al., PRC 94, 034608 (2016)

L Esym(ρ0) (MeV)

Lattimer & Steiner, EPJA 50 (2014)

Tübingen QMD and force developed by Das, Das Gupta, Gale, and Bao-An Li,

• Phys. Rev. C 67 (2003) 034611
• f elliptic-flow ratio for Au+Au @ 400 AMeV

Dan Cozma et al.

sensitivity to density

calculate DEFR (ρ)

Difference of Elliptic-Flow Ratio

ρ

Tübingen QMD and force developed by Das, Das Gupta, Gale, and Bao-An Li,

• Phys. Rev. C 67 (2003) 034611

sensitivity to density

• f elliptic-flow ratio for Au+Au @ 400 AMeV

Dan Cozma et al.

0.0 0.25 0.5 0.75

Sensitivity

0.0 0.5 1.0 1.5 2.0 2.5 3.0

/ 0

n/p n/H n/ch

0.0 0.25 0.5

DEFR

(n,ch)

Tübingen QMD and force developed by Das, Das Gupta, Gale, and Bao-An Li,

• Phys. Rev. C 67 (2003) 034611

Difference of Elliptic-Flow Ratio

ρ

sensitivity to density

P . Russotto et al., PRC 94, 034608 (2016)

ρ0 neutron star pressure p0 = 3.4 ± 0.7 MeV/fm3 Steiner, Lattimer, and Brown, ApJ 765, L5 (2013)

symmetry pressure p0 = 3.8 ± 0.7 MeV/fm3

27

„force-weighted“ density „force-weighted“ density

• pportunities

Le Fèvre et al., NPA 945 (2016)

graphics by Arnaud Le Fèvre

Au+Au

28

• pportunities

Le Fèvre et al., NPA 945 (2016) Paolo Russotto, UrQMD (2016)

<ρ> ≃ 2ρ0

within reach with Au+Au@1000

<ρ> ≃ 2ρ0

within reach with Au+Au@1000

graphics by Arnaud Le Fèvre

summary and outlook

• high-densities probed in reactions at SIS energies;

γpot = 0.9 ± 0.4 from FOPI-LAND (2011); γpot = 0.72 ± 0.19 from ASY-EOS (2016)

super-soft and super-stiff ruled out

• studies of model invariance performed;

Dan Cozma et al., PRC 88, 044912 (2013)

• elliptic flow unique regarding the sensitivity to density
• <ρ> ≃ 2 ρ0 within reach with SIS/FAIR beams
• theoretical issues: BUU consistent with QMD

short-range correlations and clustering in transport pion production in transport

• L= 72 ± 13 MeV from ASY-EOS (2016);

backups

Wenmei Guo et al., PLB 738, 197 (2014)

model dependence

elliptic flow ratio pion ratios

Gao-Chan Yong, Phys. Rev. C 93, 044610 (2016)

short-range correlations

soft super-soft

Zhang and Yong, arXiv:1605.03656

short-range correlations

modifies flow difference by <½ %

L vs flow ratio or difference

Yongjia Wang et al., Phys. Rev. C 93, 044610 (2016)

*) V.S. Uma Maheswari, C. Fuchs, Amand Faessler, L. Sehn, D.S. Kosov, Z. Wang, NPA 628 (1998)

steps towards model invariance:

tested in UrQMD: FP1 vs. FP2, i.e. momentum dep. of NNECS tested in T-QMD: soft vs. hard 190<K<280 MeV density dependence of NNECS asymmetry dependence of NNECS wave packet 2.5<L<7.0 fm2

• ptical potential

momentum dep. of isovector potential

• 0.02
• 0.01

0.0 0.01 0.02

v2

n-p

• 2
• 1

1 2

x

Cugnon Li-Machleidt K+L+Vopt+S K+L Vopt+S

supersoft superstiff elliptic flow difference, Au+Au @ 400

systematic parameter test with Tübingen QMD*)

M.D. Cozma et al., PRC 88, 044912 (2013)

conclusion: super-soft not compatible with FOPI-LAND data

clustering in UrQMD

Russotto et al. PLB 697 (2011) central 197Au + 197Au at 400 MeV/nucleon