nuclear structure and dynamics at the limits reiner krücken for the nustar collaboration physik...
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Nuclear structure and dynamics at the
limits
Reiner Krückenfor the NuSTAR collaboration
Physik Department E12Technische Universität München
&Maier-Leibnitz-Laboratory
for Nuclear and Particle Physics
RISING to the Challenges
Bill Gelletlyfor the Surrey nuclear physics group
Centre for Nuclear and Radiation PhysicsPhysics 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 Modelw/ configuration interaction
Ab initio• GFMC• NCSM• CC
Towards a predictive (and unified) description of nuclei
Realistic interactions• AV18, CD Bonn + 3N• EFT
Effective interactions• Vlow-k, VUCOM, G-matrix (+3N)
Superheavy elementsNuclear Structure at the extremes
New shell gaps through residual interaction
Neutron skins
Shell quenching bydiffuse surface
New shell gaps through residual interaction
harmonic oscillator+ spin-orbit+centrifugal
diffuse surfaceneutron rich+ spin-orbit
Halos
11Li
9Li
2n
Soft collective modes
FAIR: Facility for Antiproton and Ion Research
Primary Beams
• 1012/s; 1.5-2 GeV/u; 238U28+
• Factor 100-1000 over present in intensity
Secondary Beams
• Broad range of radioactive beams
up to 1.5 - 2 GeV/u; • up to factor 10 000 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 SuperFRS
NESR
CRRESR
GSI todayGSI today
Future FacilityFuture Facility
ESR
SUPERconducting FRagment Separator
Primary Beams
• 1012/s; 1.5-2 GeV/u; 238U28+
• Factor 100-1000
Secondary Beams
• up to factor 10 000
3 x 9.75° SC Dipole Unit
SuperferricMultiplet
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 BranchReactions with Relativistic Radioactive Beams
(R3B)
Reactions in complete kinematics
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 110Zr) increased neutron skin
-3
-1
1
3
5
7
9
11
13
15
96 106 116 126 136 146 156 166 176 186 196
Neutron number N
Sn
[MeV
]
Pb Isotope
Neutron number N
How to find a shell gap: Sn values
Shellclosure
Pairing
Neutron dripline
Pb Isotopes
Neutron separation energies
Laser spectroscopy and precision masses (MATS & LASPEC)
highest precision masses
2-n
eu
tron
sep
ara
tion
en
erg
y
Rb Spins, Moments isotope shifts
D. Lunney et al. Rev. Mod. Phys. 75 (2003) 1021
40 45 50 55 60 65
10
15
20
25
N (Z = 37)
S 2n (
MeV
)
Isoto
pe sh
ifts
0.0
0.5
1.0
1.5
<r 2> (fm
2)
N=82
Probing shell closures: Decay Spectroscopy (DESPEC)
A. Jungclaus et al., PRL 99, 132501 (2007)A. Jungclaus et al., PRL 99, 132501 (2007)
no shell quenching information on excited
states needed !!
-decay Q-value: 130Cd less bound Quenching of N=82 shell
I. Dillmann, PRL91 (2003) 162503
1h11/2 neutrons
1h11/2 protons
1g7/2 protons
11/2-
7/2+
Reduced spin-orbit or tensor force?
T. Otsuka et al., PRL 97 (2006) 162501
T. Otsuka et al., PRL 95 (2005) 232502
j<
j>
j’>
j’<
protons
neutrons
RIBbeams
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=3L=1
P||
(HISPEC, R3B)
Momentum distribution:- L of knocked-out particle
GXPF1A
56Ti
f 5/2
p 1/2p 3/2
xx
L=1
A. Gade
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)
124Sn
132Sn
Photoabsorption
Coulomb excitation
130Sn
P. Ring et al.
δrRn-Rp
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
fromRESR
• charge densities from (e,e) scattering• collective modes via (e,e’) scattering • single-particle structure from (e,e’N) reactions
The EXL experiment
Electroncooler
RIB‘s from the Super-FRS
Inelastic scattering Isoscalar Giant Monopole resonance
isospin dependence of incompressibilityElastic proton scattering Matter distribution
Neutron skins from Antiprotons
A A-1
p
H. Lenske, P. KienlePLB647 (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 modificationof pion decay constant
Pion-Nucleus Optical potential related to neutron skin
In medium modification of quark condensate
205Pb
Kolomeitsev et al. PRL90 (2003) 092501
The aims of NUSTAR @ 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