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Nuclear matter at HIRFL-CSR in Lanzhou Zhigang Xiao D epartment of Physics, Tsinghua University

Conference on Strangeness in Quark Matter Oct. 05-10, 2008, Tsinghua Uni., Beijing. Nuclear matter at HIRFL-CSR in Lanzhou Zhigang Xiao D epartment of Physics, Tsinghua University. Collaborators THU: M. Zhang IMP : H. S. Xu, G. M. Jin, F. Fu, G. C. Yong

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Nuclear matter at HIRFL-CSR in Lanzhou Zhigang Xiao D epartment of Physics, Tsinghua University

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  1. Conference on Strangeness in Quark Matter Oct. 05-10, 2008, Tsinghua Uni., Beijing Nuclear matter at HIRFL-CSR in LanzhouZhigang XiaoDepartment of Physics, Tsinghua University Collaborators THU: M. Zhang IMP : H. S. Xu, G. M. Jin, F. Fu, G. C. Yong Texas A&M: B. A. Li SJTU: L. W. Chen GSI： FOPI collaboration

  2.  Content  Introduction to HIRFL－CSR1  Machine and detector status  Nuclear matter at GeV/u regime  Equation of state of asymmetric nuclear matter  Softening ofEsym() at supra-density from  probe  Why HIRFL-CSR  Stopping and compression in HIC  More simulations for CSR energy regime  Summary 1. Heavy Ion Research Facility at Lanzhou—Cooling Storage Ring

  3. North SFC – Sector Focusing Cyclotron K＝69  Ek(12C) = (0.5－17) MeV/u Building 2# SFC: up to 10 AMeV SSC: up to 100 AMeV SSC SSC – Separated Sector Cyclotron K＝450  Ek(A/q=2)  110 MeV/u 。 SFC 。 CSRe • CSRm – Cooling Storage Ring main • Ek(A/q=2)  1000 MeV/u Building 6# 。 CSRm CSRm: 1.1 AGeV(12C6+), 2.8 GeV(p) CSRe: 0.76 AGeV (12C6+) HIRFL-CSR Complex

  4. HIRFL-CSR Photos

  5. HIRFL-CSR Research Programs • Nuclear Physics • Nuclear spectroscopy, Super-Heavy Nuclide (SHN), • RIB physics • Reaction dynamics and nuclear matter • Atomic Physics • Highly Charged Ions, High Energy Density Matter, Molecular & cluster beams • Material Science • Radio-biology & cancer therapy with heavy ions • Accelerator physics

  6. Current beams at CSR Ions：12C6+， 36Ar18+，129Xe27+, 86Kr Energy:1 GeV/u for C & Ar in CSRm Intensity:3.2 mA (1.61010) for C-7 MeV/u in CSRm 10 mA (7109) for C-600 MeV/u in CSRm 1.2 mA (4108) for Ar-368 MeV/u in CSRm 0.5 mA (1108) for Xe-235 MeV/u in CSRm 15 mA (8109) for C-660 MeV/u in CSRe ~1108 for Kr-450 MeV/u in CSRm Experiment:RIB from RIBLL2, test with isochronous mode in CSRe , ∆M/M~10-6 Slow-extraction:1.2 s for Ar-368MeV/u from CSRm 3.0 s for 12C4+-300 MeV/u from CSRm

  7. ETE Phase I(External Target Experiment – Phase I) •  detectors:4 segmented C • MWDC:6, with conventional technique lover detectors • ToF Wall:3, 2 layers of BC408 bars, 30 bars/layer, readout fromboth ends with PMT (R7525) • Neutron Wall:14 layers, 18 paddles/layer, readout from both ends with PMT (R7724); BC408 only for the first two layers, sampling type (BC408+Fe) for the others

  8. To be constructed within 4 years if approved. Key part！！ ETE Phase II • New Detectors • -ball • (CsI(Tl) array • MWPC • (inside dipole) • Si-strip array • (inside dipole) • TPC? • (at target region) • Possible Physics • For RIB Physics • For EoS of asymmetry nuclear matter • For high baryon density matter

  9.  Content  Introduction to HIRFL－CSR1  Machine and detector status  Nuclear matter at GeV/u regime  Equation of state of asymmetric nuclear matter  Softening ofEsym() at supra-density from  probe  Why HIRFL-CSR  Stopping and compression in HIC  More simulations for CSR energy regime  Summary 1. Heavy Ion Research Facility at Lanzhou—Cooling Storage Ring

  10. ~1 GeV/u :Compressibility Esym Equation of State of nuclear matter • Consistence Maintained at 0 • Unknown at > 0

  11. Probe 2: -/+ ratio B. A. Li PRC71 (2005)014608 Probes to Esym() II: high density

  12. Complete set of  multiplicity W. Reisdorf et al. for FOPI collaboration NPA 781(2007) 459

  13. C. B. Das, S. Das Gupta, C. Gale, B. A. Li PRC67(2003) 034611 IBUU04: B. A. Li Phys. Rev. Lett. 88, 192701 (2002) L. W. Chen et al., PRC 76, 054316 G.C.Yong et al., PRC73(2006)034603 B.-A. Li, PRC 69 (2004) 064602 Asymmetric energy at high density： little known

  14. Revisit  and its relevance of Esym() Multiplicity Multiplicity reproduced by the model, But shows insignificant sensitivity on the Esym().

  15. R(-/+) vs Ebeam Eb>0.6GeV/u: Undistinguishable Eb<=0.6GeV/u: Soft Esym seems to be favored. Softening of Esym() at supra-normal density

  16. Switch x at <0 Switch x at >0 High density effect • High density effect is the main contribution

  17. X=1 soft X=-1 hard Density profile High density achieved in the central region, where a larger N/Z asymmetry is experienced with a softer Esym().  Higher R(-/+) .

  18.  Content  Introduction to HIRFL－CSR1  Machine and detector status  Nuclear matter at GeV/u regime  Equation of state of asymmetric nuclear matter  Softening ofEsym() at supra-density from  probe  Why HIRFL-CSR  Stopping and compression in HIC  More simulations for CSR energy regime  Summary 1. Heavy Ion Research Facility at Lanzhou—Cooling Storage Ring

  19. Sensitivity vs Ebeam beam energy stopping sensitivity Measurement of pion emissions at CSR energy range (<1GeV for HI) may helps to resolve the Esym()!

  20. Stopping  Transverse/Longitudinal symmetry  Ni+Ni  Pb+Pb Eb=0.4,0.8 and 1.2 GeV/u • Normalized to same system size FOPI collaboration et al., In preparation

  21. Pb+Pb vs. Ni+Ni FOPI collaboration et al., In preparation Stopping hierarchy: Higher Ebeam less stopping; Lighter system less stopping; Heavier mass less stopping;

  22. F. Fu, et al. PLB666(2008)359 More Compressed More Stopping More sensitive on EOS Larger signal Stopping vs. compression/pressure

  23. Less Stopping • Less compression • Lower gain for baryon density Stopping vs Density gain F. Fu, Z. G. Xiao et al., PLB666(2008)359

  24. Sensitivity vs System size The increasing sensitivity of pion probe on Esym() is evident when passing from Ca+Ca to Au+Au

  25. Summary • we report the status of the new facility CSR at Lanzhou which will be able to make rather contributions in nuclear EOS study, particularly on Esym() at high density. The sub-GeV/u energies, for the maximum nuclear stopping verified experimentally, are advantageous for converting the beam energy to compression up to 2~30. • Within an isospin dependent transport framework, the most recent and complete  data set an partial constraint on Esym(). For the first time we observed a softening of Esym() at supra-density, which might have many astrophysical indications. Further simulations show that at CSR energies, the sensitivity of the  probe on Esym() increases with decreasing the beam energy or increasing the system size.

  26. P.C. Sereno et al. Science, Nov. 13, 1298(1998).(Spinosaurid) Imaginewhat it’ll be in the next 50 yrs, 100 yrs, …? For about 50 yrs Spinosaurid has been vegetarian, now it’s a carnivore. The fate of Spinosaurid … Thank you!

  27. Backup slides start here: Not likely distinguishable!

  28.  Some advantages at CSR energy regime •  Density as high as 2~30 , varying rapidly with beam energy; • Maximum stopping, maximum sensitivity on the Esym(); More for s, • Most copious produced, copious information of isospin effect; • NOT influenced by the problem of clustering in transport. • ……

  29. Sensitivity vs System size Larger colliding system more compressed and the sensitivity on Esym() increases with system size.

  30. Stopping in IQMD (II) • Above 400 MeV/u, for the heavy system, flow and stopping are close to data

  31. 1932中子发现后，就有中子星假设，34年Baade等人就预言这种星体在超新星爆发后可能产生，1967年Bell和Hewish等人发现第一颗辐射脉冲星，Hulse和Taylor等便发现第一颗双星体，其中便有一颗中子星存在。1932中子发现后，就有中子星假设，34年Baade等人就预言这种星体在超新星爆发后可能产生，1967年Bell和Hewish等人发现第一颗辐射脉冲星，Hulse和Taylor等便发现第一颗双星体，其中便有一颗中子星存在。 • 70年代QCD的渐进自由性质提出以后，人们便意识到在高密的中子星核心内可能存在至夸克物质的相变。1984年Witten就提出由u、d、s等组成的奇异夸克星体可能存在，即夸克星。 • 中子星半径约10公里，质量1~2M早期通过中微子发射冷却，而后期通过表面光子发射致冷。对脉冲星而言， 转动周期在ms量级。 • 表面壳层由重核与简并电子构成。向中心方向压力和密度增加，电子可能被核俘获，同时中子游离于重核之外，因此系统逐渐向A＋n＋e这样的体系过度。最后，重核解体为中子、质子和电子体系。在密度大于1ns时，可能存在(由于密度增加导致e化学势最终大于的质量，其Fermi面变得不再稳定， e向的衰变可能产生)。当密度增至数倍ns的时，其它奇异的成分，如超子(同理)，K凝聚和解禁闭夸克等可能存在。

  32. NS with quark core Strange Quark Star n p e  Outer (A+e) & Inner (A+n+e) crust u d s e u d s 0 - K-    n p e  n p e  NS with Meson condensation NS with hyperon core R ~10km Neutron Star

  33. M-R relation of Neutron Star 最大质量与EOS相关，图中曲线为Mmax>1.44的EOS 通常认为，Stiff EOS 意味着大的最大质量和大的半径。对于>Msolar的星体来说，只有充分soft的EOS才可能有R<12km 最大的质量（不是某个星体的质量）为高密EOS性质控制。核子之外的自由度的引入将会使EOS变软；只是观测到的已知的最大星体1.44Ms太小，不足以确定高密核物质中的组分和星体的结构信息。 另一方面，NS半径则主要取决于ns附近的核力性质，尤其是对称能项的密度依赖行为。这主要是因为NS的半径与内部压力（1.5～3ns）之间的关系（RP^－1/4=const）。在 ns附近，P与K，K’和Esym有关，但是在高密度时，K和K’的贡献几乎抵消，剩下的仅仅是Esym的密度依赖行为。

  34. Probe 5：IMF correlation function • Waiting for transport studies Z. G. Xiao, R. J. Hu et al., PLB 639 (2006) 436

  35. M-R relation of Neutron Star 除了Mmax和R之外，NS热学性质的观测也是我们了解强相互作用物质性质的途径。现在人们意识到，Esym（rho）对于中微子冷却率起关键作用，这不仅是因为Esym控制冷却率，还决定了在何种密度下，奇异子、超子或凝聚现象可以发生。这些奇异现象的出现会使得冷却率加快。 Core-crust transition controlled by Esym at high density Critical density for condensation depends on the symmetry energy of nucleonic matter

  36. 1932 中子发现, 34，中子星预言 1967,Bell和Hewish，1st pulsar Hulse和Taylor， 1st 双星体 70年代，QCD的渐进自由性质 1984，Witten，夸克星可能性 R～10km，W 1~2M，对脉冲星而言， 转动周期在ms量级。 早期通过中微子发射冷却，后期通过表面光子发射致冷。 表面壳层：重核与简并电子 向A＋n＋e体系过度。 最后，重核解体为中子、质子和电子体系。 >1ns时，可能存在。 >~3ns的时，其它奇异的成分，如超子，K凝聚和解禁闭夸克等可能存在。 Crust 中子星有一个固态的Crust，包绕着一个uniform的液态物质，后者可视为含有很少量质子的中子物质。这个Crust具有一定的观测效应，但是在计算curst的转动惯量分量时，需要知道何时发生了从nuclei致uniform matter的相变，这需要Esym信息。 在忽略表面和Coulomb效应的近似下，这可以考虑为纯npe物质变得不稳定产生两相（原子核和核子海）分离的临界密度。

  37.  Clustering: system size dependence 1 Heavier system favors more clustering. 2 Lower Eb(slower/longer expansion) favors clustering. 3 Nature is purely “coalescence”? If not, what else?

  38. 斜率 dN/dA(y0) = C(y0)*exp(sA) 5 What cause different y0 dependence behavior in light and heavy system? 6 Correlation between stopping and clustering?

  39. Clustering in IQMD (I) • Yield and EOS 4 Sensitivity on EOS Helps NOT to resolve EOS!

  40. dN/dY in IQMD • Clustering physics is enriched in this regime, but not fully understood; transport does not repeat the data in the highly transparent systems or species! • Again, due to the large discrepancy between the yield in the model and in data, EOS constraint is unlikely conclusive.

  41. North • Location I • Nuclear spectroscopy • drip-line nuclei, Nuclear chemistry, SHN Building 2# SFC: up to 10 AMeV SSC: up to 100 AMeV SSC SFC CSRe 。 。 • Location II • Nuclear spectroscopy • H.I. collision dynamics • RIB Physics • drip-line nuclei & SHN Building 6# CSRm CSRm: 1.1 AGeV(12C6+), 2.8 GeV(p) CSRe: 0.76 AGeV (12C6+) HIRFL-CSR Experiments on Nuclear Physics

  42. HIRFL-CSR Experiments on Nuclear Physics North • Location III (within 2~3 years) • RIB Physics • EoS of Asymmetric nuclear matter • High baryon density nuclear matter • Location V (within 1year) • Spallation • Application Building 2# SFC: up to 10 AMeV SSC: up to 100 AMeV SSC SFC CSRe Building 6# • Location IV (on-going) • mass measurement • decay spectroscopy • Location VI (planned) • Hadron Spectroscopy • Isospin Physics • Spin physics CSRm CSRm: 1.1 AGeV(12C6+), 2.8 GeV(p) CSRe: 0.76 AGeV (12C6+)

  43. Beam signal for slow extraction in CSRm 36Ar18+-368MeV/u Slow-extraction Success 1.2s Spill length: 1.2s Main frequency: 50Hz 2008.01.10 15:00

  44. Esym() controls NS structural properties • Proton fraction • M-R relation • c for D-Urca • Transition density • …… Phy. Rep. 442(2007) 109; NPA777(2006)479 PRC76(2007),025801; PRC75(2007) 015801 PRC74 (2006),035802 Astro. J. 676 (2008) 1170 Phy. Rep. 411(2005) 325 B. A. Li et al., PLB 642, 436 (2006)

  45. Neutron Skin in 208Pb Fast nucleon emission Isospin scaling Probes to Esym() I: low density Isospin diffusion Asy-soft at normal or sub-normal density.

  46. 2007.12.07 Mass Measurement of RIBs in CSRe Isochronous Mode: g = gtr = 1.395, ToF

  47. Slow extraction for 12C4+-300MeV/uin CSRm From Scintillation Crystal Monitor 2008.05.21 03:31 3s

  48. Soft Hard Hard Soft B. A. Li et al., PRL88 (2002) 192701 Probes to Esym() II: high density Probe 1: n/p differential flow: Asy-Soft  Smaller differential flow

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