Physics of Exotic Nuclei Witold Nazarewicz (UT/ORNL) University of Tokyo, May 27, 2005 • Introduction • Landscape/Playground • Studies of Exotic Nuclei • Exotic Nuclei and the Cosmos • Radioactive Nuclear Beams • Summary
The Nobel Prize in Physics 2004 Gross, Politzer, Wilczek heavy nuclei few body quarks gluons vacuum quark-gluon soup QCD nucleon QCD few body systems bare NN force many body systems effective NN force The Nuclear Many-Body Problem radioactive beams electron scattering relativistic heavy ions
pion p+ ~140 MeV QCD scale 1000 MeV g g g g g g g g g g g deuteron ~3 MeV N-binding scale pion-mass scale _ _ _ _ _ _ _ _ _ d d d d d d d d d d d 10 MeV 100 MeV u u u u u u u u u u u u d collective ~1 MeV Energy Scales in Nuclear Physics
superheavy nuclei proton drip line neutron stars neutron drip line Nuclear Landscape 126 stable nuclei 82 r-process known nuclei terra incognita 50 protons 82 rp-process 28 20 50 8 28 neutrons 2 20 8 2
Density Functional Theory self-consistent Mean Field Shell Model Ab initio Theory: roadmap 126 82 r-process 50 protons rp-process 82 28 20 50 8 28 neutrons 2 20 8 2
Ab initio: GFMC, NCSM, CCM (nuclei, neutron droplets, nuclear matter) S. Pieper, ENAM’04 1-2% calculations of A = 6 – 12 nuclear energies are possible excited states with the same quantum numbers computed
Diagonalization Shell Model (medium-mass nuclei reached;dimensions 109!) Honma, Otsuka et al., PRC69, 034335 (2004) and ENAM’04 Martinez-Pinedo ENAM’04
Nuclear DFT From Qualitative to Quantitative! Deformed Mass Table in one day!
Ab Initio Density Functional Theory asymptotic freedom… The ultimate goal of the physics of nuclei is to develop a unified, predictive theory of nucleonic matter We need access to neutron- and proton-rich nuclei • What is the mechanism of nuclear binding? • How do fission and fusion work? • What are the phases and symmetries of nucleonic matter?
Shells 10 experiment experiment 0 Nuclei theory -10 theory Shell Energy (MeV) 0 20 28 50 -10 discrepancy 82 126 0 diff. 1 experiment -10 20 60 100 Number of Neutrons 0 58 92 198 138 -1 Shell Energy (eV) Sodium Clusters spherical clusters theory 1 0 -1 deformed clusters 50 100 150 200 Number of Electrons
Change of Shell Structure in Neutron Rich Nuclei Near the drip lines nuclear structure may be dramatically different. First experimental indications demonstrate significant changes No shell closure for N=8 and 20 for drip-line nuclei; new shells at 14, 16, 32
Do very long-lived superheavy nuclei exist? What are their physical and chemical properties? Three frontiers, relating to the determination of the proton and neutron drip lines far beyond present knowledge, and to the synthesis of the heaviest elements What are the limits of atoms and nuclei?
lifetimes > 1y Superheavy Elements S. Cwiok, P.H. Heenen, W. Nazarewicz Nature, 433, 705 (2005)
Neutron Drip line nuclei 6He 4He 8He HUGE D i f f u s e d PA IR ED 5He 7He 9He 10He
n n p p p n Skins and Skin Modes
r excited 1Su and1Pu states + N N Diabatic potential energy surfaces for excited electronic configurations of N2 Excitation spectrum of N2 molecule Rotational Transitions ~ 10 meV Vibrational Transitions ~ 100 meV Electronic Transitions ~ 1 eV
Nuclear collective motion Rotational Transitions ~ 0.2-2 MeV Vibrational Transitions ~ 0.5-12 MeV Nucleonic Transitions ~ 7 MeV What is the origin of ordered motion of complex nuclei? Complex systems often display astonishing simplicities. Nuclei are no exception. It is astonishing that a heavy nucleus, consisting of hundreds of rapidly moving protons and neutrons can exhibit collective motion, where all particles slowly dance in unison.
E fission/fusion exotic decay heavy ion coll. Q0 Q E shape coexistence Q1 Q2 Q
Based on National Academy of Science Report We are all made of stardust (debris from stellar explosions) Question 3How were the elements from iron to uranium made ?
RIA intensities (nuc/s) Mass known > 1012 102 1010 10-2 Half-life known nothing known 10-6 106 Nuclear Input (experiment and theory) Masses and drip lines Nuclear reaction rates Weak decay rates Electron capture rates Neutrino interactions Equation of State Fission processes Supernova E0102-72.3 n-Star KS 1731-260 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 p process s-process 4U1728-34 331 330 Frequency (Hz) r process 329 328 327 10 15 20 Time (s) rp process Nova Crust processes T Pyxidis stellar burning protons neutrons
r (apid neutron capture) process The origin of about half of elements > Fe(including Gold, Platinum, Silver, Uranium) Supernovae ? Neutron star mergers ? Open questions: • Where does the r process occur ? • New observations of single r-process events in metal poor stars • Can the r-process tell us about physics under extreme conditions ? Swesty, Calder, Wang
neutron capture timescale: ~ 0.2 ms Rapid neutroncapture b-decay Seed Equilibrium favors“waiting point” (g,n) photodisintegration Proton number Neutron number The r-process
Nuclear Structure and Reactions Nuclear Theory forces methods extrapolations low-energy experiments Nuclear Astrophysics
X-ray bursts (1735-444) 15 s ms burst oscillations 4U1728-34 331 330 Frequency (Hz) 329 Superbursts 328 327 (4U 1735-44) 10 15 20 Time (s) StrohmayerBhattacharyya et al. 2004 6 h 18 18.5 time (days) Lines during bursts EXO0748-676 Cottam, Paerels, Mendez 2002 Deciphering observations of Hubble, CHANDRA …
Tests of the Standard Model Parity violation studies in francium 126 82 Weak interaction studies in N=Z nuclei EDM search in radium 50 protons • Specific nuclei offer new opportunities for precision tests of: • CP and P violation • Unitarity of the CKM matrix • … 82 28 20 50 8 28 neutrons 2 20 How will we turn experimental signals into precise information on physics beyond the standard model? 8 2
Worldwide RNB Effort EURISOL
QCD • Origin of NN interaction • Many-nucleon forces • Effective fields subfemto… nano… Complex Systems Giga… Cosmos femto… Physics of Nuclei Quantum many-body physics Nuclear Astrophysics • 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 • How does complexity emerge from simple constituents? • How can complex systems display astonishing simplicities? How do nuclei shape the physical universe?
The study of nuclei is a forefront area of science. It is this research that makes the connection between QCD phenomena, many-body systems, and the cosmos. What binds protons and neutrons into stable nuclei and rare isotopes? What is the origin of simple patterns in complex nuclei? Where and how did the elements from iron to uranium originate? Summary Connecting Nuclei with the Universe