Properties of stellar matter in supernova II explosions.

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Properties of stellar matter in supernova II
explosions.
Hirschegg-2006
A.S.Botvina
GSI, Darmstadt, Germany, and Institute for
Nuclear Research, Moscow, Russia
(special thanks for collaboration to
I.N.Mishustin, W.Trautmann, K.Langanke, Th.Janka)
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fragmentation of nuclear matter in nuclear
reactions and astrophysical processes
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The symmetry-term coefficient ? in the
multifragmentation scenario
Esym ?(N-Z)2/A
?
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A.S.Botvina and I.N.Mishustin, Phys.Lett. B584,
233 (2004) Phys.Rev. C72, 048801 (2005)
including photons
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fixed electron share, similarity to nuclear
multifragmentation
Agt4
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including ß-equilibrium and neutrino capture at
high densities
A
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phase diagram of stellar matter caloric curve
nuclear heat capacity has a maximum
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adiabatic behavior (important for collapse and
explosion hydrodynamical simulations)
??Gad
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electron capture rates, Re (per nucleon, per
second)
using K.Langanke et al. Phys.Rev.Lett. 90,
241102 (2003)
Independent particle model, Gamow-Teller
transitions dominate
dependence on the symmetry energy of nuclei
Esym?(A-2Z)2/A
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possible contribution of nuclei produced in dense
environment to nucleosynthesis
super-heavy elements may be produced
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Conclusions
1. There is a similarity of nuclear matter
conditions reached in multifragmentation
reactions and during a collapse and explosion of
massive stars. In the both cases the nuclear
statistical equilibrium can also be established.
2. The statistical multifragmentation model,
which has been previously successfully
applied for nuclear multifragmentation, is
generalized for astrophysical conditions.
Parameters of the model can be adjusted from
multifragmentation experiments, in particular,
using data on the symmetry energy of nuclei in
dense hot medium.
3. The calculations demonstrate a broad variety
of nuclei produced in stellar matter,
including very large and neutron rich ones, which
parameters depend also on the symmetry energy.
This may have important consequences for
nucleosynthesis of heavy and super-heavy
elements.
4. Rates of electro-weak reactions on nuclei in
stellar matter can be essentially changed
depending on modification of nucleus properties,
in particular, their symmetry energy in medium.
There should be effects on composition and
thermodynamical properties of the matter.
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Conditions of equilibration Rates of main
nuclear reactions
evaporation (of neutrons,...) tevap?/Gn Gn-
evaporation width
photo-nuclear reactions tphoto1/(v???s?A) s?A0.1
A fm2 ??2?(3)/p2T3/(?c)3
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Isoscaling and coefficient ?
ALADIN 12C 112,124Sn A.Le Fevre et al.,
Phys.Rev.Lett 94, 162701 (2005)
aT -4? (Z12/A12-Z22/A22)
S(N)Y(124Sn)/Y(112Sn)Cexp(NaZß)
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adiabatic behavior (important for collapse and
explosion hydrodynamical simulations)