Transcript Document
Nuclear Structure’07: Exciting, Broad, Relevant Witold Nazarewicz (Tennessee) • • • • • Introduction Progress report Connections Relevance Perspectives 1 Bordone, 1528 Schenk, Valk, 1700 Mercator, 1648 Introduction National Academy 2007 RISAC Report Nuclear science is entering a new era of discovery in understanding how nature works at the most basic level and in applying that knowledge in useful ways. Nuclear structure. A FRIB would offer a laboratory for exploring the limits of nuclear existence and identifying new phenomena, with the possibility that a more broadly applicable theory of nuclei will emerge. FRIB would investigate new forms of nuclear matter such as the large neutron excesses occurring in nuclei near the neutron drip line, thus offering the only laboratory access to matter made essentially of pure neutrons; a FRIB might lead to breakthroughs in the ability to fabricate the superheavy elements with larger neutron numbers that are expected to exhibit unusual stability in spite of huge electrostatic repulsion. Nuclear astrophysics. A FRIB would lead to a better understanding of key issues by creating exotic nuclei that, until now, have existed only in nature’s most spectacular explosion, the supernova. A FRIB would offer new glimpses into the origin of the elements, which are produced mostly in processes very far from nuclear stability and which are barely within reach of present facilities. A FRIB would also probe properties 4 of nuclear matter important to theories of neutron-star crusts. Weinberg’s Laws of Progress in Theoretical Physics From: “Asymptotic Realms of Physics” (ed. by Guth, Huang, Jaffe, MIT Press, 1983) Third Law: “You may use any degrees of freedom you like to describe a physical system, but if you use the wrong ones, you’ll be sorry!” Nuclear Structure Theory of Nuclei Overarching goal: To arrive at a comprehensive and unified microscopic description of all nuclei and low-energy reactions from the the basic interactions between the constituent protons and neutrons – Self-bound, two-component quantum many-fermion system – Complicated interaction based on QCD with at least two- and threenucleon components – We seek to describe the properties of finite and bulk nucleonic matter ranging from the deuteron to neutron stars and nuclear matter; including strange matter – We want to be able to extrapolate to unknown regions There is no “one size fits all” theory for nuclei, but all our theoretical approaches need to be linked. We are making great progress in this direction. Questions and challenges Questions that Drive the Field o o o o How do protons and neutrons make stable nuclei and rare isotopes? What is the origin of simple patterns in complex nuclei? Physics What is the equation of state of matter made of nucleons? of nuclei What are the heaviest nuclei that can exist? o When and how did the elements from iron to uranium originate? o How do stars explode? o What is the nature of neutron star matter? Nuclear astrophysics o How can our knowledge of nuclei and our ability to produce them Applications benefit the humankind? of nuclei – Life Sciences, Material Sciences, Nuclear Energy, Security Phys. Rev. Lett. 99, 192501 (2007) Nature 449, 1022 (2007) No shell closure for N=8 and 20 for drip-line nuclei; new shells at 14, 16, 32… number of nuclei ~ number of processors! Ab initio: GFMC, NCSM, CCM (nuclei, neutron droplets, nuclear matter) Quantum Monte Carlo (GFMC) 12C 13C No-Core Shell Model 40Ca Coupled-Cluster Techniques Faddeev-Yakubovsky Bloch-Horowitz … Input: • Excellent forces based on the phase shift analysis • EFT based nonlocal chiral NN and NNN potentials deuteron’s shape GFMC: S. Pieper, ANL 1-2% calculations of A = 6 – 12 nuclear energies are possible excited states with the same quantum numbers computed The nucleon-based description works to <0.5 fm Diagonalization Shell Model (CI) (medium-mass nuclei reached;dimensions 109!) Honma, Otsuka et al., PRC69, 034335 (2004) and ENAM’04 Martinez-Pinedo ENAM’04 13 A remark: physics of exotic nuclei is demanding Interactions Interactions Many-body Correlations Configuration interaction • Mean-field concept often questionable • Asymmetry of proton and neutron Fermi surfaces gives rise to new couplings • New collective modes; polarization effects • Poorly-known spin-isospin components come into play • Long isotopic chains crucial Open Channels Open channels • Nuclei are open quantum systems • Exotic nuclei have low-energy decay thresholds • Coupling to the continuum important •Virtual scattering •Unbound states •Impact on in-medium Interactions Large-scale Calculations S. Cwiok, P.H. Heenen, W. Nazarewicz Nature, 433, 705 (2005) Stoitsov et al., PRL 98, 132502 (2007) • Global DFT mass calculations: HFB mass formula: m~700keV • Taking advantage of high-performance computers Prog. Part. Nucl. Phys. 59, 432 (2007) The nucleus is a correlated open quantum many-body system Environment: continuum of decay channels `Alignment’ of w.b. state with the decay channel Thomas-Ehrmann effect 14 4946 Nd 12C+n 3/2 3685 3089 1/2 3502 2365 1943 O n 15 N p 12 C 12C+p ~ 4 p 4h 1/2 13C 7 15 0 13N 6 ~ 0 p 12 0 16O Spectra and matter distribution modified by the proximity of scattering continuum 7162 6049 P. Navratil et al., PRC 73, 065801 (2006) G. Hagen et al., nucl-th/0610072 NCSM CC K. Nollett et al., nucl-th/0612035 GSM GFMC Connections How does the physics of nuclei impact the physical universe? • What is the origin of elements heavier than iron? • How do stars burn and explode? • What is the nucleonic structure of neutron stars? X-ray burst 4U1728-34 331 330 329 328 327 10 15 Time (s) 20 Nova n-Star T Pyxidis protons neutrons KS 1731-260 Connections to complex many-body systems ! • • • • • • • Understanding the transition from microscopic to mesoscopic to macroscopic Quantum Chaos and the Random Matrix Theory Superconductivity Loosely bound and open systems Dynamical symmetries and Quantum Phase Transitions Coulomb frustration Fermionic sign problem 21 subfemto… • How does complexity emerge from simple constituents? • How can complex systems display astonishing simplicities? nano… •Origin of NN interaction •Many-nucleon forces •Effective fields femto… Giga… Physics of Nuclei How do nuclei shape the physical universe? •In-medium interactions •Symmetry breaking •Collective dynamics •Phases and phase transitions •Chaos and order •Dynamical symmetries •Structural evolution •Origin of the elements •Energy generation in stars •Stellar evolution •Cataclysmic stellar events •Neutron-rich nucleonic matter •Electroweak processes •Nuclear matter equation of state Relevance Nuclear Science Applications Medi cal Di agnostics and Therapy Radiography Computerized t omography P osit ron emission t omography MRI (regular) MRI (with polarized noble gases) Photon therapy P article-beam therapies Safe ty and Nati onal Se curi ty Airport safety and security Large-scale x-ray scanners Nuclear materials det ection Arms control and nonproliferation Stockpile stewardship Tritium production Space-radiation health effect s Semi-conduct or performance in radiation environments Food sterilization En ergy Produ ction an d Exploration Nuclear react ors Oil-well logging R&D for next generation nuclear react ors Art an d Archaeology Authentication Nuclear dating Material Analysis Activation analysis Accelerat or mass spectrometry Atom-trap trance analysis Forensic dosimetry P roton-induced x-ray emission Rutherfold backscattering Ion-induced secondary-ion emission Muon spin rotation Environmen tal Appli cation s Climate-change monit oring Pollution control Groundwater monit oring Ocean-current monit oring Radioactive-waste burning Materials Te sting and Modifi cati on Trace-isotope analysis Ion implantation Surface modifications Flux-pinning in high-T c superconduct ors Free-electron lasers Cold and ultra-cold neutrons Single-event effort s Microphone filters LRP’07 report MRI of inhaled polarized 129Xe by a human Eac h frame is a snapshot of the absorption of the polarized gas in the lung tissue during a normal resp iration cycle. The 129Xe concentration is color coded with red indicating the highest concentration. Atom Trap Trace Analysis: 81Kr dating Relevance of Nuclear Theory… Addressing national needs •Advanced Fuel Cycles • neutron-reaction cross sections from eV to 10 MeV • the full range of (n,f), (n,n’), (n,xn), (n,g) reactions • heavy transuranics, rare actinides, and some light elements (iron, sulfur) • Quantified nuclear theory error bars • Cross sections input to core reactor simulations (via data evaluation) • BETTER CROSS SECTIONS AFFECT both SAFETY and COST of AFC reactors. • Science Based Stockpile Stewardship • Radiochemical analysis from days of testing: inference on device performance shows final products but not how they came to be. • Typical example Yttrium charged particle out reaction. LESS THAN 10% of cross sections in region measured. • Theory with quantifiable error bars is needed. These two examples point to the relevance of Nuclear Theory to OTHER programs of national interest. Quantifiable theory error bars is a key desire. Room for large-scale computing (SciDAC) AFC workshop proceedings: www.sc.doe.gov/np/program/docs/AFC_Workshop_Report_FINAL.pdf The Stewardship Science Academic Alliance program workshop: http://www.orau.gov/2007SSAAS/index.htm Perspectives 2007 Long Range Plan Recommendations for Nuclear Science 1. We recommend completion of the 12 GeV Upgrade at Jefferson Lab. The Upgrade will enable new insights into the structure of the nucleon, the transition between the hadronic and quark/gluon descriptions of nuclei, and the nature of confinement. 2. We recommend construction of the Facility for Rare Isotope Beams, FRIB, a world-leading facility for the study of nuclear structure, reactions and astrophysics. Experiments with the new isotopes produced at FRIB will lead to a comprehensive description of nuclei, elucidate the origin of the elements in the cosmos, provide an understanding of matter in the crust of neutron stars, and establish the scientific foundation for innovative applications of nuclear science to society. 3. We recommend a targeted program of experiments to investigate neutrino properties and fundamental symmetries. These experiments aim to discover the nature of the neutrino, yet unseen violations of time-reversal symmetry, and other key ingredients of the new standard model of fundamental interactions. Construction of a Deep Underground Science and Engineering Laboratory is vital to US leadership in core aspects of this initiative. 4. The experiments at the Relativistic Heavy Ion Collider have discovered a new state of matter at extreme temperature and density—a quark-gluon plasma that exhibits unexpected, almost perfect liquid dynamical behavior. We recommend implementation of the RHIC II luminosity upgrade, together with detector improvements, to determine the properties of this new state of matter. 28 Experiment TRIUMF NSCL RIKEN GANIL HRIBF FRIB Future major facilities Existing major dedicated facilities Radioactive Ion Beam Facilities Worldwide GSI ISOLDE Radioactive Ion Beam Facilities Timeline ISOLDE ISAC-II ISAC-I SPIRAL2 SPIRAL FAIR SIS RIBF RARF NSCL HRIBF CARIBU@ATLAS In Flight ISOL Fission+Gas Stopping FRIB Beam on target 2000 2005 2010 2015 2020 What is needed/essential? • Young talent • Focused effort • Large collaborations unedf.org • Data from terra incognita • High-performance computing • Interaction with computer scientists Connections to computational science 1Teraflop=1012 flops 1peta=1015 flops (next 2-3 years) 1exa=1018 flops (next 10 years) Jaguar Cray XT4 at ORNL No. 2 on Top500 • 11,706 processor nodes • Each compute/service node contains 2.6 GHz dual-core AMD Opteron processor and 4 GB/8 GB of memory • Peak performance of over 119 Teraflops • 250 Teraflops after Dec.'07 upgrade • 600 TB of scratch disk space Example: Large Scale Mass Table Calculations Science scales with processors Jaguar@ M. Stoitsov, HFB+LN mass table, HFBTHO Even-Even Nuclei The SkM* mass table contains 2525 even-even nuclei A single processor calculates each nucleus 3 times (prolate, oblate, spherical) and records all nuclear characteristics and candidates for blocked calculations in the neighbors Using 2,525 processors - about 4 CPU hours (1 CPU hour/configuration) Odd and odd-odd Nuclei The even-even calculations define 250,754 configurations in odd-A and odd-odd nuclei assuming 0.5 MeV threshold for the blocking candidates 33 Using 10,000 processors - about 24 CPU hours A typical run for the whole even-even mass chart contains about 2731 different bound nuclear states which identify the ground states of 1527 even-even nuclei. At the end of the run: 2032 converge for up to 500 iterations 404 converge up to 1000 iterations 123 converge up to 2000 iterations 152 converge up to 6000 iterations 26 do not converge 34 Broyden Mixing 100 194 Rn, HFB+LN, Nsh=20 Sly4 + mixed dpairing Error 10-1 10-2 10-3 10-4 10-5 Linear mixing Broyden M=3 Broyden M=7 0 10 20 30 40 50 60 70 80 90 100 Number of iterations 35 Bimodal fission in nuclear DFT A. Staszczak, J. Dobaczewski, W. Nazarewicz, in preparation S. Umar and V. Oberacker Phys. Rev. C 76, 014614 (2007) nucl-th/0612017 TDHF description of heavy ion fusion Supernova Modeling Blondin, Mezzacappa, Nature 445, 58 (2007) Conclusions The study of nuclei makes the connection between the Standard Model, complex systems, and the cosmos • Exciting science; old paradigms revisited • Interdisciplinary (quantum many-body problem, cosmos,…) • Relevant to society (national security, energy, medicine…) • Theory gives the mathematical formulation of our understanding and predictive ability • Experiment provides insights and verification • New-generation computers provide unprecedented opportunities Guided by data on short-lived nuclei, we are embarking on a comprehensive study of all nuclei based on the most accurate knowledge of the strong internucleon interaction, the most reliable theoretical approaches, and the massive use of the computer power available at this moment in time. The prospects look good. Thank You Backup Example: Surface Symmetry Energy Microscopic LDM and Droplet Model Coefficients: P.G. Reinhard et al. PRC 73, 014309 (2006) Shell effects in metastable minima seem to be under control P.H. Heenen et al., Phys. Rev. C57, 1719 (1998) Important data needed to fix the deformability of the NEDF: • absolute energies of SD states • absolute energies of HD states Advantages: • large elongations • weak mixing with ND structures Different deformabilities! Nuclear DFT Global properties, global calculations S. Goriely et al., ENAM’04 M. Stoitsov et al. * Global DFT mass calculations: HFB mass formula: m~700keV • Taking advantage of high-performance computers Cold gases, BEC’s, neutron matter Connections to complex many-body systems ! • Dilute Fermions with large/infinite scattering length [impact in nuclear, cold-atom physics, condensed matter and astrophysics (neutron star crust, cooling)] PRL 91, 050401 (2003) 172 citations •EOS, pairing gap near unitarity predicted at T=0 and T>0 PRL 96, 090404 (2006) 43 citations •DFT description: PRA 74, 041602(R) (2006) • EFT/RG treatment of cold atoms: cond-mat/0606069 • Pairing in asymmetric Fermi gasses: PRL 97, 020402 (2006) • Coupled cluster theory, method of moments [impact in nuclear physics and quantum chemistry] PRL 92, 132501 (2004) • DMRG approach to nuclei and open quantum systems Rep. Prog. Phys. 67, 513 (2004) •Description of weakly-bound and unbound states of many-Fermion systems PRL 97, 110603 (2006) • Shell model with random interactions [quantum chaos,quantum dots] PRL 93, 132503 (2004); PRB 72, 045318 (2005); PRB 74, 165333 (2006) • Quantum phase transitions in mesoscopic systems [impact in nuclear, cold-atom, molecular physics] PRL 92, 212501 (2004); NPA 757, 360 (2005) • Applications of SM and DFT to atomic physics: PRA66, 062505 (2002) • Pairing correlations in ultra-small metallic grains (studies of the static-to-dynamic crossover): RMP 76, 643 (2004) 43