Presentation is loading. Please wait.

Presentation is loading. Please wait.

高等原子核理论 Advanced Nuclear Theory 北京大学物理学院 技术物理系 裴俊琛 Junchen Pei, School of Physics, Peking University 2014.9, Beijing.

Similar presentations


Presentation on theme: "高等原子核理论 Advanced Nuclear Theory 北京大学物理学院 技术物理系 裴俊琛 Junchen Pei, School of Physics, Peking University 2014.9, Beijing."— Presentation transcript:

1 高等原子核理论 Advanced Nuclear Theory 北京大学物理学院 技术物理系 裴俊琛 Junchen Pei, School of Physics, Peking University , Beijing

2 Contents Background and developments Earlier Nuclear models Ab inito and Shell Model Density Functional Theory Nuclear forces Nuclear superfluidity Symmetries and collective motion DFT extensions Reaction Theory 2 Advanced Nuclear Theory----J.C. Pei

3 Challenges in nuclear physics Superheavies RNB facilities offer unprecedented opportunities to access unstable nuclei -3- Progress In Computing Nuclei and Cold Atoms

4 RNB facilities around the world FRIB FAIR RIBF SPAIRL-II Argonne, HRIBF, HIRFL-CSR, Why RNB? Advanced Nuclear Theory----J.C. Pei -4-

5 How to study nuclear physics Reaction-observation-nuclear models Different reaction mechanism Observations: decays, fragments, emissions  structures Models: many-body Hamilton and nuclear forces Advanced Nuclear Theory----J.C. Pei -5-

6 Background Nuclear theory at different resolutions/precision, with different degrees of freedom Effective nuclear forces associated nuclear many-body problems Multi-Physics overlaps and observables in different aspects Advanced Nuclear Theory----J.C. Pei -6-

7 本科生 — 研究生 本科:书本上基础知识学习, 主要是为了考试 研究生:主要目的是研究,学习为了研究和解决问题, 创造新知识,职业训练(独立科研的能力)

8 导师 --- 学生 导师: 提供平台, 建议方向,教授方法, 解决难题 学生: 实现物理想法,团队合作,自我提升 导师 --- 学生之间 interface : 沟通,信任 不愤不启,不悱不发 《论语》

9 魔鬼在细节中 不要 Assume 你的结果:结果没有好坏, unexpected 往往 才是有价值的! 时间在点滴之中

10 物理 < 格物 对比 创新 变化 理论与实验 观测量直接对比 Pesudo 间接对比 实验与预言 不同模型 不同方法 新的理论,思想 新的 Hamiltonian 新的观测量 新的模型方法 新的实验和理论精度 新的参数 系统性对比发现变化 归纳已知外推未知 创新引起变化 关于物理的思考 --- 裴俊琛 2013 PKU

11 核物理的前景 物质结构不同的层次划分: 宇观,宏观,分子,原子,核,核子,夸克 不同层次的都有自身特点和问题并且不可替代 对交叉的物理问题有贡献:量子多体,核天体, QCD, 甚至生物,金融等 超级计算机的发展: petaflop (天河 1 号 2.6- 天河 2 号 38 ) —exaflop FRIB (Facility for Rare Isotope Beams) 应用:能源,信息,医疗 ……

12 原子核理论的发展与前沿 The Developments and Frontiers of Theoretical Nuclear Physics 北京大学物理学院 裴俊琛 Junchen Pei, School of Physics, Peking University

13 Outline Nuclear structure: macroscopic and microscopic perspectives Modern nuclear theory and supercomputing Nuclear theory and multi-disciplinary subjects Summary and outlook Advanced Nuclear Theory----J.C. Pei -13-

14 Nuclear liquid drop model and fission Advanced Nuclear Theory----J.C. Pei -14- Nuclear liquid drop model of Fission: the competition between Coulomb and surface tension (1939), By Bohr and Wheeler Fission calculations on the first computer Eniac (1946), By Frankel (1947) Problems: Can not explain the asymmetric fission Z>104 nuclei is unstable against spontaneous fission Magic numbers are missed (N=2, 8, 20, 28, 50, 82, 126, …..)

15 Explanation of liquid drop model Fermi Gas model (non-interacting Fermions) Advanced Nuclear Theory----J.C. Pei -15- a Boundary condition (quantization) Can explain the liquid drop model’s volume energy, surface energy, symmetry energy (due to different proton neutron numbers) Problem: magic numbers are missed Solution: we need nuclear interactions beyond Pauli principle

16 Magic numbers and shell effects Magic numbers: Shell effects in finite Fermi systems Advanced Nuclear Theory----J.C. Pei -16- Magic numbers in atoms: 2, 10, 18, 32, 54, 86 Magic numbers in nuclei: 2, 8, 20, 28, 50, 82… Strong spin-orbit coupling in nuclei Mayer and Jenson (1949) General shell effects in quantum dots, droplets, alkali clusters, metal nanowires …

17 Macroscopic plus microscopic Oscillations in level density (quantum effects), 1967 E = E liquid-drop + E shell-correction Very successfully for describe nuclear bulk properties: mass, deformation, second minimum Advanced Nuclear Theory----J.C. Pei -17- classical quantum

18 Nuclear many-body Hamiltonian Generally: Advanced Nuclear Theory----J.C. Pei -18- Problem: Can not be solved exactly for N>3 Solution: solving the many-body problem with a finite model space Solving the equation with different precision with different many-body techniques: ab inito, configuration interaction, density functional theory

19 Solving the Many-body problem Start from the independent-particles Assume correlated many-body wavefunction can be expanded in the Fock space Fock space is the combination of various Hillbert spaces with different quasiparticles Advanced Nuclear Theory----J.C. Pei -19- (A Hilbert space) Diagonalization: A slater determinant

20 Modern Nuclear Forces Phenomenogical terms: Argonne v18 Meson exchange theory: CD-Bonn chiral perturbative theory: N3LO, three-body forces Lattice QCD calculations: residual interactions of quark clusters Effective nuclear forces: Renormalization: G-matrix, V low-k Advanced Nuclear Theory----J.C. Pei -20-

21 Nuclear physics at multi-resolutions Advanced Nuclear Theory----J.C. Pei -21- Ab inito CI DFT Collective models Nuclear physics Hadron physics resolution

22 Overlaps are important Advanced Nuclear Theory----J.C. Pei -22-

23 Recent developments in nuclear theory Ab inito model study of 3-body forces Ab inito model study of nuclear reactions Advanced Nuclear Theory----J.C. Pei -23- E Drip-line of O isotopes Conclusion: 3-body force is important Exceptional long life time of C14 NCSM+RGM: provide important benchmark for reactions in astrophysics and NIF

24 Recent developments in nuclear theory UNEDF project in US Universial Nuclear Energy Density Functional involve 19 institutions and 50 researchers Computer science, applied math, nuclear theorists Advanced Nuclear Theory----J.C. Pei -24-

25 Challenges and opportunities Advanced Nuclear Theory----J.C. Pei -25- Superheavies RIB facilities offer unprecedented opportunities to access unstable nuclei

26 Latest nuclear landscape Advanced Nuclear Theory----J.C. Pei -26- From J. Erler et al., Nature, 486, 509(2012)

27 Drip-line nuclei Continuum coupling effects Open quantum systems Advanced Nuclear Theory----J.C. Pei -27-

28 Halo structures Halos (1990s) Deformed Halo (Ne38)? Advanced Nuclear Theory----J.C. Pei -28-

29 Shell structures at drip-lines Advanced Nuclear Theory----J.C. Pei -29-

30 New collective motion mode Advanced Nuclear Theory----J.C. Pei -30- Collective oscillation between core and the halo/skin Low energy E1 transition (pygmy resonances)

31 Treatment of Continuum Advanced Nuclear Theory----J.C. Pei -31- Deep bound states in BCS become quasiparticle resonances in HFB theory due to continuum coupling. HFB is superior to BCS for describing weakly-bound systems where continuum coupling becomes essential Box solution: bound states, continuum and embedded resonances are treated on an equal footing; L 2 discretization leads to a very large configuration space(expensive) Deep bound states in BCS become quasiparticle resonances in HFB theory due to continuum coupling. HFB is superior to BCS for describing weakly-bound systems where continuum coupling becomes essential Box solution: bound states, continuum and embedded resonances are treated on an equal footing; L 2 discretization leads to a very large configuration space(expensive) HFB G.S.: BCS G.S.: JP et al. PRC, 2011 HFB includes generalized quasi-particle correlations; while BCS is a special quasiparticle transformation only on conjugate states.

32 Answers to nuclear astrophysics Advanced Nuclear Theory----J.C. Pei -32-

33 Neutron stars Related to nuclear equation of state Advanced Nuclear Theory----J.C. Pei -33- Pasta A neutron star of 2.0 sun mass (2010)

34 Nuclear mass limits How to chose the target, bombard, and the collision energy Hot fusion vs cold fusion? Advanced Nuclear Theory----J.C. Pei -34-

35 Nuclear spin limits The highest spin in the universe : 65hbar Advanced Nuclear Theory----J.C. Pei -35-

36 Nuclear Temperature limits Fission and neutron evaporation competition at high temperatures It becomes symmetric fission at high temperatures Advanced Nuclear Theory----J.C. Pei -36-

37 Radioactive Beams Facilities Great opportunities in 5 years Advanced Nuclear Theory----J.C. Pei -37-

38 Supercomputing Three legs of nuclear physics: experiments, theory, supercomputing Without supercomputing, ab inito, large scale DFT, continuum treatment are impossible New architures: multi-core+GPU (why: moving data is expensive) From Tianhe-1 to Tianhe-2, 20 times faster Advanced Nuclear Theory----J.C. Pei -38-

39 Novel DFT infrastructure Advanced Nuclear Theory----J.C. Pei -39- API 1. do A 2. do B if A 3. do C 4. do D if A WorldTaskQueue ThreadPool Task dependencies: managed by Futures MainMPI Multi-resolution ADaptive Numerical Scientific Simulation  CS infrastructure: Task-oriented: MPI, Global arrays, multi-threaded, futures (asynchronous computation), loadbalance

40 Dialogue with other physicists Talk with condensed matter, cold atoms on many-body problems, superfluidity Talk to astrophysics on the evolution of universe, neutron stars Talk to high energy physics on testing standard model, AdS/CFT Advanced Nuclear Theory----J.C. Pei -40-

41 Summary and outlook The Nucleus is such a unique finite quantum system, presenting intriguing physics RIB facilities provide great opportunities and challenges for nuclear theory The development of modern nuclear theory is closed related to the capability of supercomputers Big collaborations, multi-disciplinary dialogues are very useful How about the future? Advanced Nuclear Theory----J.C. Pei -41- Thanks for your attention!

42 Advanced Nuclear Theory----J.C. Pei -42-


Download ppt "高等原子核理论 Advanced Nuclear Theory 北京大学物理学院 技术物理系 裴俊琛 Junchen Pei, School of Physics, Peking University 2014.9, Beijing."

Similar presentations


Ads by Google