A need for reliable transport codes -- a plea from the experimentalists

Transcription

1 A need for reliable transport codes -- a plea from the experimentalists Transport 214, Shanghai, January 8-12, 214 曾敏兒 etty Tsang, NSCL/MSU

2 Wish List from Experimentalists (From Trento 29) 1. Realistic sequential decay models 2. Physics interpretations less dependent on models 3. Consistencies on more than one observables. High densities: pions, n, p flow (v1, v2, radial flow), clusterization 4. Discrepancies from different models can be explained Generic or specific codes for n/p ratios observable 6. One or two slides in answers to critics of the transport models! 7. Establish data base for testing with all codes! Future workshops 1. Comparisons of more sophisticated observables Source functions (two particle correlations). Pion multiplicity & flow for 1-2MeV collisions. Inclusions of cluster formation; A=3 particles, t/ 3 He. Too many parameters s NN, m*, momentum dependence mean fields, Pauli locking guidance to standardize the input variables in the models and help to design experiments to constrain these parameters.

3 Nuclear Equation of State Mathematical Relationship between energy, temperature, pressure, density in nuclear matter V central r V tensor Nuclear Force What is the nature of the nuclear force? Nuclear Structure What binds protons and neutrons into stable nuclei and rare isotopes? Nuclear Astrophysics What is the nature of neutron stars and dense nuclear matter? E/A (,) = E/A (,) + 2 S() = ( n - p )/ ( n + p ) = (N-Z)/A

4 压强 Density dependence of Symmetry Energy E/A (,) = E/A (,) + 2 S(); Danielewicz, Lacey, Lynch, Science 298,1592 (22) metric matter = ( n - p )/ ( n + p ) = (N-Z)/A 1 P (MeV/fm -3 ) 1 RMF:NL3 Akmal Fermi gas Flow Experiment Kaons Experiment FSU Au / 密度 Flow constrains the EOS and rules out some results from RMF theory. Note: analysis requires understanding of transport models. 密度 The metry energy dominates the uncertainty in the n-matter EOS. It influences: n-star radii and moments of inertia. Proto-neutron star cooling rates. Exotic phases in neutron star interior. All interpretations of HIC data depend on transport models.

5 压强 Density dependence of Symmetry Energy E/A (,) = E/A (,) + 2 S(); Danielewicz, Lacey, Lynch, Science 298,1592 (22) metric matter = ( n - p )/ ( n + p ) = (N-Z)/A 1 P (MeV/fm -3 ) 1 RMF:NL3 Akmal Fermi gas Flow Experiment Kaons Experiment FSU Au / 密度 Flow constrains the EOS and rules out some results from RMF theory. Note: analysis requires understanding of transport models. S L K 3 18 密度 All interpretations of HIC data depend on transport models. S o E L 3 3 P 2...

6 Isospin Diffusion( 同位旋扩散 ) observable to study E with Heavy Ion Collisions( 重离子碰撞 ) Tsang et al., PRL 92 (24) 6271 弹核 Projectile 124 Sn S()=12.5(/ o ) 2/3 +C (/ o ) g i Tsang, Shi et al., PRL92, 6271(24) g i =2 stronger g i =2 g i =1/3 weaker Target 112 Sn 靶核 Isospin Diffusion; low, E beam ao-an Li et al., Phys. Rep. 464, 113 (28) Tsang, Zhang et al., PRL122, 12271(29)

7 S=12.5(/ o ) 2/3 + C s,p (/ o ) g i 2s 2 analysis with ImQMD5 ImQMD IUU4 What are the theoretical errors? o K L S S P E L 3 3

8 S=12.5(/ o ) 2/3 + C s,p (/ o ) g i o K L S S P E L 3 3 ImQMD IUU4 What are the theoretical errors? Differences from cluster production? Should differences between models attribute to errors? 2s 2 analysis with ImQMD5

9 NUSYM13 talk by Akira Ono With cluster correlations Without cluster correlations

10 EoS of ametric matter -- Constraints from Heavy Ion Collisions (HIC) at low density.a. rown,prl85(2)5296 Tsang et al,prl12,12271(29) o K L S E E/A (,) = E/A (,) + 2 S(); = ( n - p )/ ( n + p ) = (N-Z)/A

11 Tsang et al. PRL (29) o K L S E Constraints on Symmetry Energy NuSYM1

12 Constraints on Symmetry Energy NuSYM11 Isobaric Analogue States NPA 818, 36 (29) heavy ion collisions PRL 12,12271(29) Finite Droplet Range Model PRL18,5251(212) p elastic scattering PRC82,44611(21) Pygmy Dipole Resonances PRC 81, 4134 (21) neutron-star radius PRL18,112(212) E S o L 3 K Tsang et al. C 86, 1583 (212)

13 Constraints from nuclear structure and reactions with credible uncertainties NuSYM13 & ICNT213 A Way Forward: Review paper from ICNT213

14 Experimental Observables: n/p yield ratios ImQMD_sky ( 张英逊 ) n and p potentials have opposite sign. n & p energy spectra depend on the metry energy softer density dependence emits more neutrons at low density. Experimental goals: To measure p and n energy spectra and compare to models Reduce model sensitivity to cluster formation by constructing coalescence invariant n and p.

15 Isoscaling and chemical potentials Z. Chajecki He: x1-2 t: x1-1 R 21 =Y 2 /Y 1 ; 2= 124 Sn+ 124 Sn; 1= 112 Sn+ 112 Sn

16 Reproduce the n & p energy spectra E/A=5 MeV ImQMD_sky ( 张英逊 ) Data: D. Coupland M. Youngs

17 Symmetry Energy and effective nucleon mass. Liu et al. PRC 65(22)4521 Mass splitting increases with density and ametry. Larger effect at high energy?

18 Nucleon Effective Masses ImQMD_sky ( 张英逊 ) LE ( 谢文杰, 张丰收 )PRC(R) 88,6161(213) E k (MeV) ImQMD_sky & LE show the same trends. n/p ratios are higher for m n *<m p * Sensitivity is at high E kin Optimum E beam

19 Nucleon Effective Masses Confrontation with data Need correct data Need proper Cluster description Use coalescence invariant double ratios ImQMD_sky ( 张英逊 ) Data: D. Coupland, M. Youngs

20 Lessons from LE: Reproduce more than one observable or one system over a range of particle kinetic energy and incident energies. Measurements: Spectra; n/p single and double ratios; Isospin diffusion ImQMD_sky ( 张英逊 )

21 New observations of Neutron Stars Neutron Star observations M NS ~ 2M sun Large E or stiff EoS at high large radius Small E or Soft EoS at ~2 Small mass

22 New observations of Neutron Stars (masses) Lattimar & Prakash Heavy Neutron Star masses rule out soft EOS

23 New observations of Neutron Stars (radius/radii) Lattimar & Prakash S. Guillot, et al Astrophys. J. 772, 7 (213), Steiner et al Small Neutron Star radius rules out nearly all EOS

24 New NS radius and mass observation suggests exotic form of density dependence of Symmetry energy Neutron star radius (Rutledge, Gulliot) AV14+UVII Wiringa, Fiks, & Fabrocini 1988 softening EoS at ~ 2 qlmx HIC@2 S. Guillot, M. Servillat, N. A. Webb, and R. E. Rutledge, Astrophys. J. 772, 7 (213),

25 Symmetry 2 to explore neutron star radii(us) SE@2 can only be explored on earth with Heavy Ion Collisions. SE@> requires strong support from transport model community Symmetry Energy science has high impact factors Symmetry Energy Collaboration IMP, Lanzhou

26 Panel Discussions (Saturday PM) (1). Initialization: Ning Wang (GXNU), Jun Xu (SINAP, CAS) (2). Momentum dependence and energy conservation: Ying-Xun Zhang (CIAE), Wen-Jie Xie (NU) (3). Fluctuations in transport models: Paolo Napolitano (IPNO, Orsay, France), Guo-Qiang Zhang (SINAP, CAS) (4). Clusterization, light and heavy fragments: Li Ou (GXNU), Gao-Chan Yong (IMP, CAS) (5). Particle production, spectral functions: Zhao-Qing Feng (IMP, CAS, China), Pawel Danielewicz (MSU, USA) (6). Experimental observables: Zhi-Gang Xiao (Tsinghua University), Yvonne Leifels (GSI, Darmstadt, Germany) (7). Future workshops and homework: Feng-Shou Zhang (NU), Yu-Gang Ma (SINAP, CAS, China) Please join one of the groups you are interested in!

27 A need for reliable transport codes -- a plea from the experimentalists Nightmare scenario: Theoretical Challenge Transport models -- different codes give contradictory results. Need to reproduce both pions and flow observables with the same code.