Exotic Nuclei and Neutron Stars IPN Orsay 18092006

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Exotic Nuclei and Neutron Stars IPN Orsay
18/09/2006
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Aim working group of theorists and
experimentalists interested in the physics of
neutron stars links with the new generation of
radioactive beam facilities?Perspectives
experimental and/or theoretical projects and
regular meetings for discussing proposals
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Plan

• Brief description of a neutron star. Properties,
  observables, links with experimental and
  theoretical nuclear physics
• Structure of a neutron star (mass and radius)
  (equation of state, symmetry energy, novel
  phases). Theoretical approaches. Role of
  experiments in nuclear physics.
• An example of what we can learn from experiments
  with exotic nuclei. Neutron skin thickness and
  the radius of a neutron star.
• Evolution of a star (cooling time).
  Superfluidity. Role of experiments in nuclear
  physics.
• Program of the meeting

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Isospin asymmetryI(N-Z)/(NZ)Strong
asymmetries Neutron-rich nuclei and neutron
starsNuclei. I up to ? 0.2 for stable
nuclei.and with the new generation radioactive
beam facilities? (0.3?)Neutron Stars. I could
be up to ? 0.9 in the interior.
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After evolution (thermonuclear reactions) of
massive stars (M? 8 M?) (?107 years) -gt supernova
explosion . Slow cooling for millions of years.
Typical values R ? 10 km M ? 1.4 M?
Saturation density ?0 0.16 fm-3 -gt ? 2.5 ? 1014
g/cm3
EXOTIC NUCLEI
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• STRUCTURE of a neutron star (mass and radius).
  Masses measured in binary systems. Radii measured
  through fits of thermal spectra.
• EVOLUTION of a neutron star (neutrino emission,
  cooling time).

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Mass measurements of neutron stars in binary
systems
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2.5
3
3.5
0.5
1
1.5
Mass (M?)
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Theoretical approach
Compute the properties of nucleon matter.
Microscopic many-body methods using realistic
nucleon-nucleon potentials and phenomenological
relativistic and non-relativistic mean field
theories EQUATION OF STATE (EOS). Energy density
versus pressure.
EoSs can differ at lower and higher densities
(with respect to the saturation
density). Differences between symmetric nuclear
matter EoSs and neutron-rich stellar matter EoSs
(density dependence of symmetry energy)
EoS is typycally softened by the existence of
novel phases (hyperons,)
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Mass-radius diagram. Three classes of equations
of state Nuclear stars Hybrid stars Strange stars
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Central densities
MASS/RADIUS
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Typel and Brown. Lattimer and Prakash. Horowitz
and Piekarewicz. Relation between ?R and R
?Rltrn2gt1/2-ltrp2gt1/2
Calculated neutron skin thickness of nuclei
versus the radius of 1.4M? stars
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Cooling time of a neutron star
ROLE OF SUPERFLUIDITY (PAIRING) Due to the energy
gap ? in the excitation spectrum neutrino
processes are exponentially suppressed when Tltlt?
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Program

• 10.00 Collective modes. H.J. Woertche (KVI)
  neutron skins (?R) -gt star radii, cooling,
  incompressibility, symmetry energy
• 10.25 Fusion and evaporation cross section.
  Density dependence of symmetry energy. N. Le
  Neindre (IPNO)
  low-density nuclear matter, EoS, symmetry
  energy
• 10.50 Pair transfer. D. Beaumel (IPNO)
  superfluidity in neutron-rich systems
• 11.15 Coffee break
• 11.40 Angular distributions. Optical potential
  determinations. P. Roussel-Chomaz (Ganil)
  interpretation of data for neutron-rich nuclei
• 12.05 Laser spectroscopy a method to extract the
  deformation from charge radius measurements. F.
  Le Blanc (IPNO)
  neutron skins and deformations
• 12.30 Decompressing neutron star matter and the
  r-process nucleosynthesis. S. Goriely (IAA, ULB)
  
  neutron stars
  and nucleosynthesis, symmetry energy
• 12.55 Tidally ignited nucleosynthesis in star
  near black hole. B. Carter (LUTH, Observatoire de
  Meudon)
  dense matter
  and nucleosynthesis
• Lunch and coffee
• 14.30 Hypernuclei and experimental determinations
  of the hyperon-nucleon potentials. T. Saito (GSI)
  
  hyperons
  in neutron stars
• 14.55 Exotic nuclei _at_ Spiral2. M. Lewitowicz
  (Ganil)
• 15.30 Road map towards experimental and
  theoretical proposals