paths in nuclear structure - laboratory for nuclear science · reproduce nuclear structure theory...
TRANSCRIPT
Paths in Nuclear Structure
Donald Geesaman
Physics Division
Argonne National Laboratory
2
Why Paths?
“The mission of Nuclear Physics is to understand the origin, evolution and structure of baryonic matter in the universe – the matter that makes up stars, planets and human life itself.”
As we stand on the shoulders of our progress, we now see over the walls of the “maze” to the clear paths forward.
3
What does this mean to me?
Given a lump of nuclear material – real or hypotheticalWhat are its properties?What bounds its existence?Why does it display such amazing regularities?Where does it come from?What fundamental forces are at work?What forces were needed to create it, but now seem to have disappeared from view?
What is it good for?– advancing our understanding of what the universe looks like
and how we come to be here– advancing technology
4
Scope of the problem: Nuclear reactions control the time-scales of the evolution of the universe.The origin of nuclei provides extreme examples
Binding of the deuteronDeuteron Binding Energy, 2.2 MeV ~ 2(Mn-Mp)~ (md-mu) ~mu ~ md
N-N Interaction Range
Role of lack of mass 5 and 8 stable nuclei– 8Be unbound by 92 keV– Big Bang nucleosynthesis and
stellar evolution
Binding Energy of 12C ~ 100 MeV
triple alpha reaction to CarbonThe resonance energy could be predicted to 100 keV with
the hazy information of 50 years ago. (0.1%)
QCDqmdmumfqqM Λ≈+><
−= )(22
ππ
5
Craig Hogan’s “Why the Universe is just so”RMP 74, 1149 (2000)
Einstein: “What really interests me is whether God had any choice in creating the world.”
Phenomena at high energy scales may one day be understood in terms of a simple symmetry principle and at the soft scales of chemistry and biology the multitude of possible pathways may lead to the Jurassic Park principle, “Life will find a way”.
The formation of nuclei provide critical bottlenecks that govern the evolution of the universe and thus there appears to be great sensitivity to the underlying physics. [Anthropic principle?]– This has been used to search for time dependence of fundamental
dimensionless constants • Big Bang Nucleosynthesis: Δ(mq/ΛQCD)/ (mq/ΛQCD) ~ 10-3
• Oklo reactor: Δ(mq/ΛQCD)/ (mq/ΛQCD) ~ 10-9
6
Nuclear structure as Herman Feshbach taught us
J=0 nn, np, pp
J= max np only
2+
0+eeffective ~ 1.5
0+2+4+
6+
8+
8+
Rotational Band: E∝J(J+1)10+
10+
Break a J=0 pair
Strong E2 transitionswith quadrupole deformation
Shell Structure determined by mean field
Pairing- superfluidity
Volume and Surface Vibrations –plasma oscillations, giant resonances
Macroscopic Deformation and Spontaneous Symmetry breaking
Clusters – particularly α... )](1[ 200 θβYRR +=
Classical liquid drop behavior - fission
7
Why is the Time Right for Major Progress in Nuclear Structure?
• Experimental progress at JLab, MIT Bates and elsewhere to investigate QCD substructure validate hadron-based models of the nucleus.
• Effective field theories are making real progress on the interactions among nucleons.
• Progress in nuclear theory and simulation has made it clear that the solution to many long-standing issues in nuclear structure lies in the many-body physics and focused the physics questions. We know what we need to do to answer these questions.
• Astronomy and Astrophysics communities are investing heavily in new generations of observatories. Interpreting the results of these instruments requires new nuclear physics understanding.
• The progress in accelerator and target technology and experimental technique makes a bold leap forward possible.
8
The N-N interaction is strong and complicated
Very strong at short range
Complicated operator structure – 18 operators in modern forces. – spin dependent– tensor forces couple differ orbital angular momentum states– spin-orbit dependence couples orbital and spin angular momentum
Tools– Lattice – considerable ways to go– Effective field theories
• tells us what components are important• made difficult by low energy bound states
– Models• Unit χ2 fits to large body of N-N scattering data
Modern lattice QCD resultS.R. Beane et al, PRL 97 (2006)
9
Does the QCD structure lead to modifications in the nucleus: Tensor Polarization in electron-deuteron elastic scattering
PreliminaryBLASTdata
Two decades of searching for changes in baryon structure at normal nuclear matter densities have produced only limited possible signals: EMC effect
This polarization observable allows the separation of L=0 and L=2 components of the deuteron wave function.
PQCD predicts –(2)1/2 at asymptotic Q2.
10
Ab initio Calculations: a major step forward in the many-body physics
The nuclei for which we can do the many-body physics accurately are well described by interactions of nucleons with potentials : Green’s function Monte Carlo, no-core shell model, coupled cluster.
This requires accurate N-N potentials
3 – body NNN interaction
Macroscopic featureslike the mean field spin-orbit potential are sensitive to 3-body forces
The major uncertainty is in the isospin dependence of the 3-body interaction. No 3 identical nucleon scattering data
11
You need the full complexity of the N-N interaction to reproduce nuclear structure
Theory vs Experiment: Now Theory sometimes wins
An experimental report of a bound tetra-neutron state
S. Pieper PRL 90, 252601 (2003) A bound tetraneutron is incompatible with our understanding of nuclear forces.
Must include spin-orbit, tensor and spin-spin forces to account for critical features of nuclear structure.
12
2.12.01.91.81.7
Point-Proton Radius of 6He (fm)
Tanihata et al 92
Alkhazov et al 97
Csoto 93
Funada et al 94
Varga et al 94
Wurzer et al 97
Esbensen et al 97
Pieper&Wiringa 01 (AV18 + IL2)
This work 04
Navratil et al 01
(AV18 + UIX)
(AV18)
It’s far more than spectra
Reaction collision
Elastic collision
Atomic isotope shift
Cluster models
No-core shell model
Quantum Monte CarloEx
perim
ents
Theo
ries
Wang et al. atom trap measurementWith bare currents and understood meson exchange effects
•β-decay and transition rates
• Spectroscopic factors
• Nolen-Schiffer anomaly
• Cluster phenomena
• Charge radii
t1/2=807ms
13
How about big nuclei?Ab initio techniques realizable now for A<16 Even for heavy nuclei, ½ the particles are in regions of density less than 90% of central density.
Major themes– interplay of single particle and collective degrees of freedom
• Example – super-heavy nuclei– The nuclear surface as a dynamical entity.
• Example – nuclear phase transitions
)(rρ
∫∞
r
drrr )(2ρ
14
Path to a universal nuclear energy density functional
Plan for a major SciDACinitiative led by George Bertsch involving 14 institutions
A key is the ab initio calculations can provide a benchmark for evaluating the success of approximation schemes needed for heavier nuclei –already used for neutron matter research
15
Fission barrier from shell energy
shell-correction energy lowers the ground state, thereby creating a barrier against fission.
Stable superheavy nuclei: delicate balance between nuclear attraction and Coulomb repulsion
Only three “stable”:232Th (Z=90), 235,238U (Z=92)No stable nuclei with Z=84-89 and Z>92High Z Large Coulomb repulsion spontaneous fission
16
neutron number
111
112
113
114
117
115
118
116
160 162
164 166 168 170 172 174
176 178 180 182 184
152 158156154
Mt 266
Db 262 Db 263
Sg 266
Db 258Db 256 Db 260Db 257
Rf 260 Rf 261 Rf 262 Rf 263Rf 259Rf 256Rf 255 Rf 258
Bh 261 Bh 262
Rf 257
Db 261
Sg 260 Sg 261 Sg 263Sg 259
Bh 264
Bh
Hs
Ds
Sg 258
Lr 259
No 258
Lr 260
No 259
Lr 261 Lr 262
No 262No 260
Lr 258
No 257
Lr 255
No 254
Lr 254
No 253
Lr 257
No 256
Lr 256
No 255
Md 257
Fm 256
Md 258
Fm 257
Md 259 Md 260
Fm 258 Fm 259
Md 256
Fm 255
Md 253
Fm 252
Md 252
Fm 251
Md 255
Fm 254
Md 254
Fm 253
Es 255 Es 256Es 254Es 251Es 250 Es 253Es 252
Cf 255 Cf 256Cf 253Cf 250Cf 249 Cf 251 Cf 252 Cf 254
110/273110/271
111/272
CHART OF THE NUCLIDES
No
Md
Fm
Es
Cf
prot
on n
umbe
r
150
Db
Rf
Lr
No
Md
Fm
Es
Cf
Z = 114
108Hs 267Hs 265Hs 264
a
a
a
a
a
a
110/270
Hs 266
Sg 262
112/285
9.1539 s
Z/A
T1/2
E (MeV)α
110/269
Mt 268
α
EC
β-
SF
112/277
110/267
MtHs 269 Hs 270
Sg 265
Sg
a
aa
a
a
a
a
a
a
a
a
a
a
a
a a
a
aa
aa
108/275
110/279
106/271
112/284112/282
114/286 114/287
10.01
114/288
9.95
116/290
115/288115/287
113/284113/283
111/280
109/276
107/272
111/279
109/2 57
116/291
10.85 10.74
112/285
110/281
114/289
9.82
9.169.54
9.30
8.53
10.00
10.4610.59
10.12
9.75
9.71
9.02
10.37
10.33
105/268
15 ms
32 ms 87 m s
6.3 m s
0.1 s
0.15 s
0.17 s
0.72 s
9.8 s
16 h
9.7 m s
0.48 s
0.1 s0.5 m s
3.6 s
0.18 s
2.4 m in
9.6 s
34 s
0.56 s 0.63 s 2.7 s0.16 s10.20
112/2834.0 s
a
116/292
10.6616 ms
107/2 17
116/29353 ms
1.8 ms118/294
11.65
105/267
1.2 h
10.53
9.70
104/268104/2672.3 h
48 238 249Ca + U.... Cf
208 50 70Pb + Ti.... Zn
from Oganessian
Limit in Z? Cold fusion with 208Pb, 209Bi targets
Hot fusion with 48Ca beams
17
α
ATLAS at Argonne National Laboratory
PPAC at the Focal plane 40x40 DSSD
gammasphereFMA
σ ~1 µbσ/σfission ~ 10-6
18
Calorimetry:
Initial states for γ decay to g.s.
Picket fence structure ofγ-ray spectrum is characteristic of a rotational band:
IJE 32 +
=Δ γ
19
Predicted magic gaps from different models: Macroscopic/Microscopic (MM), Skyrme (SHF) & Relativistic (RMF) mean field.
Where are the magic gaps for superheavy nuclei?
one-proton drip line
one-neutron drip line
20
Key observables for deducing decay scheme:Maximum conversion electron sum energyObserved Eγ , Iγ and coincidence relationsK X-ray intensity
Long-lived isomeric states give us important information on the shell corrections
For K, the projection of J on the symmetry axis, to remain a good quantum number, the nucleus must remain axially symmetric
21
protons neutrons
Proton f5/2 orbital from above the possible Z=114 spherical shell gap !
Deformation causes the single particle levels important for superheavy nuclei to be observable at low excitation
22
neutron number
111
112
113
114
117
115
118
116
160 162
164 166 168 170 172 174
176 178 180 182 184
152 158156154
Mt 266
Db 262 Db 263
Sg 266
Db 258Db 256 Db 260Db 257
Rf 260 Rf 261 Rf 262 Rf 263Rf 259Rf 256Rf 255 Rf 258
Bh 261 Bh 262
Rf 257
Db 261
Sg 260 Sg 261 Sg 263Sg 259
Bh 264
Bh
Hs
Ds
Sg 258
Lr 259
No 258
Lr 260
No 259
Lr 261 Lr 262
No 262No 260
Lr 258
No 257
Lr 255
No 254
Lr 254
No 253
Lr 257
No 256
Lr 256
No 255
Md 257
Fm 256
Md 258
Fm 257
Md 259 Md 260
Fm 258 Fm 259
Md 256
Fm 255
Md 253
Fm 252
Md 252
Fm 251
Md 255
Fm 254
Md 254
Fm 253
Es 255 Es 256Es 254Es 251Es 250 Es 253Es 252
Cf 255 Cf 256Cf 253Cf 250Cf 249 Cf 251 Cf 252 Cf 254
110/273110/271
111/272
CHART OF THE NUCLIDES
No
Md
Fm
Es
Cf
prot
on n
umbe
r
150
Db
Rf
Lr
No
Md
Fm
Es
Cf
Z = 114
108Hs 267Hs 265Hs 264
a
a
a
a
a
a
110/270
Hs 266
Sg 262
112/285
9.1539 s
Z/A
T1/2
E (MeV)α
110/269
Mt 268
α
EC
β-
SF
112/277
110/267
MtHs 269 Hs 270
Sg 265
Sg
a
aa
a
a
a
a
a
a
a
a
a
a
a
a a
a
aa
aa
108/275
110/279
106/271
112/284112/282
114/286 114/287
10.01
114/288
9.95
116/290
115/288115/287
113/284113/283
111/280
109/276
107/272
111/279
109/2 57
116/291
10.85 10.74
112/285
110/281
114/289
9.82
9.169.54
9.30
8.53
10.00
10.4610.59
10.12
9.75
9.71
9.02
10.37
10.33
105/268
15 ms
32 ms 87 m s
6.3 m s
0.1 s
0.15 s
0.17 s
0.72 s
9.8 s
16 h
9.7 m s
0.48 s
0.1 s0.5 m s
3.6 s
0.18 s
2.4 m in
9.6 s
34 s
0.56 s 0.63 s 2.7 s0.16 s10.20
112/2834.0 s
a
116/292
10.6616 ms
107/2 17
116/29353 ms
1.8 ms118/294
11.65
105/267
1.2 h
10.53
9.70
104/268104/2672.3 h
48 238 249Ca + U.... Cf
208 50 70Pb + Ti.... Zn
from Oganessian
Limit in Z? Cold fusion with 208Pb, 209Bi targets
Hot fusion with 48Ca beams
23
Nuclear Phases/Shape TransitionsAs one adds nucleons one sees dramatic transitions in the nuclear shapes.
Generalized collective models-dynamical nuclear surface
Interacting boson models provide comparable, more microscopic descriptions
)](1[ 20 θα μμ
μYRR ∑+=
Most nuclei do not exhibit the idealized symmetries but rather lie in transitional regions.
24
Iachello discusses these as Quantum phase transitions
A QPT is a phase transition in which the control parameter is not the temperature T as in thermodynamic phase transitions, but rather the coupling constant, g, appearing in the quantum HamiltonianH= (1−g)H1+gH2
Nuclei are ideal systems to study quantum phase transitions:•They are finite systems in which the number of particles can be tuned, which changes g, thus allowing a study of scaling behavior.•They display both first and second order transitions(Erhenfest classification). In addition, recently (2000), signatures of critical behavior have been suggested, called “critical symmetries”.
25
Structural Evolution, Phase Transitions, and Critical Point Nuclei
26
2
21 0;ξξ ξ⎡ ⎤′
′′ + + − =⎢ ⎥⎢ ⎥⎣ ⎦
%% %v
z z
X(5)Bessel equation
( ) 0.ξ β =%w
Critical Point SymmetriesFirst Order Phase Transition – Phase Coexistence
E E
β
1 2
3
4
ββ
Energy surface changes with valence nucleon number
Iachello
2/1
49
4)1(
⎭⎬⎫
⎩⎨⎧ +
+=
LLνZeros of Bessel functions of order
27Zamfir
Theory Experiment
28
Related many-body problems
Finite Bose systems Quantum Dots
Also Efimov states, molecules, metal clusters ...
29
Why can’t we extrapolate tonew regions and phenomena?
Why does adding 1 proton to O bind 6 more
neutrons?Why is the size of 11Li
the same as 208Pb?
Calculations of nuclear matrix elements for
neutrino-less double beta-decay vary by
factors of 3-5.
one-proton drip line
one-neutron drip line
30
Basic “facts” of nuclear physics that may be wrong in neutron-rich nuclei
The radius and diffuseness of the neutron and proton distributions are similar
R=1.2 A1/3, a~ 0.55 fmThe magic numbers of the shell model are fixed. The deformations of the neutrons and protons are similar The valence quasi-particles are renormalized by about 0.6 by short-range correlations. The charge-independence of the strong interaction makes isospin a good quantum number
]/)exp[(11)(
aRrr
−+=ρ
This is only illustrative. There are a number of other mechanisms that also lead to changes in the shell structure as N/Z varies.
31
Following the Single Particle Levels with Changing Neutron Number
Energy difference between particle states and hole states with changing neutron number studied with single particle transfer reactions.
Single-particle transfer reaction measurements on Sn isotopes: Schiffer et al. PRL 92, 162501 (2004)
Neutron excessE
nerg
y di
ffere
nce
(MeV
)
32
Does the impact of short-range correlations change dramatically?
ΔS = Sn-Sp for neutron knockout and
Sp-Sn for proton knockout
History1960’s: Shell Model and transfer reactions assumed pure single particle states.1970’s: electron scattering showed only 60% occupancy in valence single particle states.1980’s: Understood based on short-ranged correlations.1990’s: Short-range correlations viewed as universal, approximately nucleus independent.2000’s: In nuclei far from stability, observed large changes in correlation effects.
22O 34Ar
From Gade and Tostevin, NSCL
33
Neutron SkinsClear effects in halo nuclei like 11LiPredicted large effectsaway from stabilityCritical for expectations ofnuclei and neutron stars– Equation of State– Cooling
Difficult to measure –need to calibrate hadronicprobesEagerly await JLabmeasurement in parity violating electron scattering on 208Pb –PReX
Neutron weak charge= -1/2Proton weak charge=1/2− 2 sin2ΘW = 0.038
My personal bet is these are overestimated because clustering is left out
34
Impact of Isospin Dependence of Strong Interactions
From Steiner, Prakash, Lattimer and Ellis Phys.Rept. 411 (2005) 325-375
35
Most of the energy production in the cosmos and the production ofthe chemical elements is due to nuclear reactions in stars. The Big Bang starts out forming protons and neutrons. Everythingelse results from nuclear reactions.
Carl Sagan: “We are all star dust”• Reactions during the Big Bang• Slow burning reactions in stars
4p ⇒ 4He + 2e+ + 2ν3 4He ⇒ 12C + γ79Br+n⇒γ + 80Br ⇒ 80Kr
• Fast burning reactions in nova and supernova
Neutron stars are giant drops of nuclear material weighing as much as the sun, but with a radius of 10 km.
X-rays from Crab pulsar
Low Energy Nuclear Physics is the energy source and the alchemist’s tool of element creation
Major successes
36
Core Collapse Supernova
What do we knowMost of the energy of the collapse goes into neutrinos
What do we need to know?– Effects of the neutrino properties – How is the energy transferred from the neutrinos?– What are the dynamics of the explosion?– Is this the site of the r-process?– How are the elements heavier than Fe formed?
Neutrino propertiesHow do neutrinos interact with matter?– energy transfer, neutrino processing including fission
What are the properties of the very neutron-rich nuclei?What is the fission recycling by neutrons and neutrinos?
37
One example: r-process element production
38
Neutron Stars
What are the limits on mass and radii?Is neutron matter superfluid?Do we see transition to kaon-condensed or quark matter ?Cooling– URCA cooling in neutron matter
requires large proton fraction: Yp~.11-.15
– Color superconductorsNuclear Observables:– neutron skins– N/Z dependence of giant
resonances– nuclear equation of state studies
Astronomical observations
Recent observation of high massneutron stars2.1 ± 0.2 MNice et al. astro-ph/05080502.1 ± 0.28 M , R=13.8 ± 1.8 kmOzel, Nature 441, 04858 (2006)
Correlation between neutron skin thickness in finite nucleiand pressure of β-equilibrated matter in neutron stars
39
Constraints on neutron star equations of state
Mass-Radius constraints from observations and model predictions for the mass-radius of nucleonic stars, hybrid stars and strange quark stars. (From Jaikumar, Page and Reddy)
40
Example: Neutron StarsPasta nuclei: At near nuclear matter densities, competition between Coulomb and surface interactions lead to a complex set of nuclear shapes: rods, slabs ... “nuclear pasta”. Similar effects are observed in microemulsionsand liquid crystals. Strong effects on dynamic response, including interactions with neutrinos
Is neutron matter superfluid at high densities: The high Fermi energy and short-range repulsion reduces s-wave pairing. Is p-wave interaction sufficient? Dilute systems: |kF a| > 5 at 0.3% nuclear matter densities – related to dilute Fermi gases
41
Example: Impact of Nuclear Structure on Fundamental Interactions
Neutrino-less double beta decay– Is the neutrino its own
antiparticle?– If we observe neutrino-less
double beta decay, the limit we can set on neutrino masses will be set by how well we understand the nuclear structure
For a light Majorano neutrino
2
22
02
20
2/1
),(1
ejj
j
FA
VGTo
Umm
mMggMZEG
T
∑=
⎥⎦
⎤⎢⎣
⎡−=
ν
ννν
Current uncertainty in nuclear matrix elements is a factor of 3.
Current work focuses on identifying the other nuclear observables that place the best constraints on thestructure uncertainties.
76Ge76Se
76As
νν+e-e-νν
42
Example: Impact of Nuclear Structure on Fundamental Interactions
Enhanced Electric Dipole Moments– What causes the baryon
asymmetry in the universe?
– EDM’s in nuclei can be enhanced by factors of 100-1000 due to nuclear structure.
Need multiple measurements to separate contributions of:– lepton EDM – quark EDM– T-violation in QCD
• atoms• neutron• nuclei
225Ra experiment underway at ANL bytrapping 225Ra in MOT.
43
By measurement in these unexplored regions
• We can experimentally determine the properties of the important cases to the required precision.
• We provide critical tests to guide the development of a unified model of nuclei.
• We can determine our “periodic table”.
• We can extrapolate much better to “neutron matter”.
What do we need to knowHalf of the nuclear landscape is unexplored!
44
What do we need to do this? - ExperimentAccess to this broad range of new nuclei– higher beam power– new target concepts
Ability to use all the principal experimental probes of low energy physics– Reaccelerated beams
• single particle and two-particle transfer reactions for spectroscopic factors and pair correlations
• collective excitations for emergent phenomena and interplay of single particle and collective degrees of freedom
• direct measurements of reactions at the energies they take place in stellar explosions
• new pathways to super-heavy element production– Fast beams
• farthest reach to the limits of nuclear existence• nuclear equation of state in neutron-rich matter• charge-exchange measurements of beta-strength functions
Much progress can be made at the international suite of existing and planned accelerators such as RIKEN, FAIR, GANIL, ISAC
45
There is the only one facility on the horizon that combines all these features: Rare Isotope Accelerator/Advanced Exotic Beam Laboratory
• Fast Gas Catcher to combine advantages of fragmentation and stopped beams
• Superconducting driver linacand post-accelerator for all ions from hydrogen to uranium.
• Acceleration of ions in multiple charge states to increase performance.
• Realizable designs for high power (>100 kW) targets.
• Efficient reacceleration of 1+ charge states.
46
Simplified Schematic Layout of the Rare Isotope Accelerator (RIA) Facility
• Superconducting RF DriverLinac with 400 MeV/nucleonbeams for all stable isotopesup to uranium. 900 MeV protonbeams.
• 100-400 kW of beam power.• Collects and reaccelerates
beams of unstable nuclei.
• Concept validated. No significant technical risk.
What is the Concept?
47
What are the capabilities that are optimized at RIA
Experiments with reaccelerated rare isotope beams of all elements- wide variety of nuclear structure and reaction techniquesOptimized production technique for each isotopeISOL production mechanisms for stopped and reaccelerated beams yield much higher rates for a number of elementsFactors of 10-100 higher beam intensities for most in-flight isotopes reaching further into the r-process pathHigh beam intensities at lower beam energy better suited to stop beams in gas cellFacility optimized for and dedicated to experiments with rare isotopes
48
History and current situation
NSAC Long Range Plans since 1996 have made this a priority recommendation.– 2002, RIA is the highest priority for major new construction.
2003 DOE 20-year Facilities Plan:– RIA is tied for third.
Draft Request for Proposals in 2004 – ran into disastrous 2006 budget request.The Science of RIA is under evaluation by a US National Academy committee: (RIA Scientific Assessment Committee —RISAC), report due in October.
2006 actions by DOE:5-year plan: Implement a plan to remain among the leaders in nuclear structure/astrophysic– Support R&D to start construction of a U.S. exotic beam facility for about
half the cost of RIA with unique capabilities at the end of this 5-year period.
– In DOE-speak this means a decision to go ahead in ~end of 2007 and new request for proposals in 2008.
49
By focusing on reaccelerated beams, an optimized half scale exotic beam facility is world class and complements international efforts
Relative yields for a 200 MeV/u Advanced Exotic Beam Facility (AEBL) vs RIA and ISAC
Better everywhere and the yellow regionsare uniquely available with AEBL
50
What do we need to do this? - Theory
Advances in large scale simulations.– QCD, ab initio, DFT, molecular dynamics
Exploit systematic approach of effective field theory
Deeper understanding of the microscopic descriptions of emergentphenomena
Close contact with the astrophysics, elementary particle and condensed matter communities
51
Major questions in nuclear physics
What is our periodic table?Why do nuclei show such amazing regularities?What are the properties of neutrinos?What forces seem to have disappeared from view?How do hadrons and nuclei emerge from QCD?What are the properties of hot and dense hadronicmatter?How did the properties of quark and hadronic matter affect the evolution of the universe?– How do massive stars explode?– What is the origin of the elements more massive
than Fe.
52
This is not your father’s nuclear structure
There is a unfortunate tendency in science to believe that a problem that has been unsolved for some time is no longer interesting. The fruit of nuclear structure remains quite sweet.
Aesop’s the Fox and the Grapes
53
Extra Material
54
RIA Isotope Yields
See www.phy.anl.gov for predicted yield of every isotope
These are available as isotopically pure beams.
These are typically available as fast, mixed beams.
55
RIA yields relative to GSI for in-flight beamsSimulations done using LISE++ and beam/separator parameters appropriate for each facilityIncludes beam energies and intensities, secondaries and target attenuation, charge-state losses, and attenuation in 2 wedges
56
Production Mechanisms
Reaction mechanism for highest yieldof reaccelerated beams for each
selected isotope.
Fragmentation + gas cell
ISOL
In-flight fission + gas cell
In-flight fission + gas cell
Two-step fission
The science requires that ALL production mechanisms be available