Nuclear structure and dynamics at the limits Reiner Krücken for the NuSTAR collaboration Physik Department E12 Technische Universität München & Maier-Leibnitz-Laboratory for Nuclear and Particle Physics

RISING to the Challenges Bill Gelletly for the Surrey nuclear physics group Centre for Nuclear and Radiation Physics Physics Department University of Surrey UWS -08/05/2008

Nuclear structure and dynamics at the limits Introduction The NuSTAR facility at the Super-FRS Modification of shell structure Soft modes, nuclear EOS and neutron skins Conclusions

Long Standing Questions of Nuclear Structure Physics What are the limits for existence of nuclei? –Where are the proton and neutron drip lines situated? –Where does the nuclear chart end? How does the nuclear force depend on varying proton- to-neutron ratios? –What is the isospin dependence of the spin-orbit force? –How does shell structure change far away from stability? How to explain collective phenomena from individual motion? –What are the phases, relevant degrees of freedom, and symmetries of the nuclear many-body system? How are complex nuclei built from their basic constituents? –What is the effective nucleon-nucleon interaction? –How does QCD constrain its parameters? Which are the nuclei relevant for astrophysical processes and what are their properties? –What is the origin of the heavy elements?

Mean Field Models DFT RMF Shell Model w/ configuration interaction Ab initio GFMC NCSM CC Towards a predictive (and unified) description of nuclei Realistic interactions AV18, CD Bonn + 3N  EFT Effective interactions V low-k, V UCOM, G-matrix (+3N)

Lack of predictive power of mean-field models from RIA Whitepaper Position of the neutron-dripline

Superheavy elements Nuclear Structure at the extremes New shell gaps through residual interaction Neutron skins Shell quenching by diffuse surface New shell gaps through residual interaction harmonic oscillator + spin-orbit +centrifugal diffuse surface neutron rich + spin-orbit Halos 11 Li 9 Li 2n Soft collective modes

FAIR: Facility for Antiproton and Ion Research Primary Beams /s; GeV/u; 238 U 28+ Factor over present in intensity Secondary Beams Broad range of radioactive beams up to GeV/u; up to factor in intensity over present Antiprotons Storage and Cooler Rings Radioactive beams e - - A and Antiproton-A collider 100 m UNILAC SIS 18 SIS 100/300 HESR Super FRS NESR CR RESR GSI today Future Facility ESR

SUPERconducting FRagment Separator Primary Beams /s; GeV/u; 238 U 28+ Factor Secondary Beams up to factor x 9.75° SC Dipole Unit Superferric Multiplet

Experiments with slowed and stopped beams Laser spectroscopy (LASPEC) Decay spectroscopy (DESPEC) Energy buncher / spectrometer In-flight spectroscopy (HISPEC) Precision mass measurements (MATS) Gas stopping cell

High Energy Branch Reactions with Relativistic Radioactive Beams (R 3 B) Reactions in complete kinematics

Ring Branch

Modification of shell structure - Reduction of Spin-orbit splitting ? - Role of the tensor interaction ?

Shell modification through softer potential ? T.R. Werner, J. Dobaczewski, W. Nazarewicz, Z. Phys. A358 (1997) 169 Possible signatures:  reduction of spin-orbit splitting in neutron-rich nuclei  new shell gaps (e.g. N=70 in 110 Zr)  increased neutron skin

Neutron number N How to find a shell gap: S n values Shell closure Pairing Neutron dripline Pb Isotopes Neutron separation energies

Q-values from  -decay (DESPEC)  Shortest half-lives, production rates << 1 min -1

Laser spectroscopy and precision masses (MATS & LASPEC)  highest precision masses 2-neutron separation energy Rb  Spins, Moments  isotope shifts D. Lunney et al. Rev. Mod. Phys. 75 (2003) N (Z = 37) S 2n (MeV) Isotope shifts  <r 2 > (fm 2 )

time 4 particles with different m/q Schottky Mass Spectrometry Y. Litvinov

Schottky Mass Spectrometry Sin(  1 ) Sin(  2 ) Sin(  3 ) Sin(  4 ) 11 22 33 44 time Fast Fourier Transform Y. Litvinov

Schottky Frequency in Storage Ring (ILIMA)

ILIMA mass measurements mass surveys

N=82 Probing shell closures: Decay Spectroscopy (DESPEC) A. Jungclaus et al., PRL 99, (2007)  no shell quenching  information on excited states needed !!  -decay Q-value:  130 Cd less bound  Quenching of N=82 shell I. Dillmann, PRL91 (2003)

1h 11/2 neutrons 1h 11/2 protons 1g 7/2 protons 11/2 - 7/2 + Reduced spin-orbit or tensor force? T. Otsuka et al., PRL 97 (2006) T. Otsuka et al., PRL 95 (2005) j<j< j>j> j’ > j’ < protons neutrons RIB beams J.P. Schiffer et al., PRL 92 (2004) Z=51 Sb isotopes

Single-particle structure from direct reactions Cross sections: -exclusive for excited states via gamma-decay (  AGATA)  spectroscopic factors Knock-out reaction -Peripheral collision -Possible with few particles/s P. Maierbeck et al., GSI-FRS + MINIBALL  L=3  L=1  P || (HISPEC, R3B) Momentum distribution: - L of knocked-out particle GXPF1A 56 Ti f 5/2 p 1/2 p 3/2 x x  L=1 A. Gade

Soft modes, nuclear EOS and neutron skins

Giant resonances Radioactive beams allow study of isospin dependence  probe bulk properties of nuclei  in-medium modification of NN interaction  symmetry energy  compressibility  New soft modes

Dipole Excitations of Neutron-Rich Nuclei - Symmetry Energy, Neutron Skin, and Neutron Stars - neutron skin  core vibration LAND collaboration A. Klimkiewicz, PRL subm. P. Adrich, PRL 95 (2005) 124 Sn 132 Sn Photoabsorption Coulomb excitation 130 Sn P. Ring et al.

δrδr R n -R p excitation of the neutron skin Properties of Neutron Stars Neutron-skin thickness Dipole Excitations of Neutron-Rich Nuclei - Symmetry Energy, Neutron Skin, and Neutron Stars -

Neutron skins M. Bender, et al. RMP 75 (2003) Alternative access to asymmetry parameter established methods for charge radii neutron radii difficult to measure

Electron Ion Collider (ELISe) to FLAIR from RESR charge densities from (e,e) scattering collective modes via (e,e’) scattering single-particle structure from (e,e’N) reactions

The EXL experiment Electron cooler RIB‘s from the Super-FRS Inelastic  scattering  Isoscalar Giant Monopole resonance  isospin dependence of incompressibility Elastic proton scattering  Matter distribution

Neutron skins from Antiprotons  A A-1 H. Lenske, P. Kienle PLB647 (2007) 82 P. Kienle, NIM B 214 (2004) 193 Antiproton Ion Collider (AIC) M. Wada, Y.Yamazaki annihilation cross-section at high energies proportional to mean square radius count surviving A-1 nuclei  Proton and neutron radii in the same experiment EXOpbar antprotons on atomic orbits annihilation on tail of density distribution  Halo or Skin ?

Neutron skins  Deeply bound pionic states  In medium modification of pion decay constant Pion-Nucleus Optical potential related to neutron skin  In medium modification of quark condensate 205 Pb Kolomeitsev et al. PRL90 (2003)

The aims of FAIR Nuclear Structure Physics: –Isospin dependence of effective nuclear interaction –Modification of shell structure far off stability –New effects near the driplines (halos, skins, soft modes, …) –Relevant symmetries, structural evolution, role of phase transitions Nuclear Astrophysics Studies: –Understand the origin of the heavy elements  K.H. Langanke Nuclear Reaction studies –Investigate reaction dynamics for RIB production, spallation, ADS –Dynamics in systems with weakly bound nucleons (halos, correlations, continuum)  Towards a unified description of nuclear structure and dynamics