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HIM-2009-9-26
Instability and Phase Transition in Asymmetric
Nuclei
Kyung Hee UniversitySuk-Joon Lee
Thermalized nuclear systemMedium energy heavy-ion collision RIB - AsymmetricNeutron star Short range repulsive and long range attractive Saturation, Phase transitionTow component system: 3-d of , , T He, Binary alloyPhase diagram; surface in 3-d of P, T, y or densitySymmetry energy Second order transition, Isospin fractionationCoulomb energy Beta stability line , Asymmetric phase diagramFinite system Surface energyVelocity dependent interaction Effective mass
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S.J. LeeA.Z. MekjianPRC56,2621(1997)
S.J.LeeA,Z,MekjianPRC45,1284(192)
H. Mueller and B,D. Serot, PRC.52, 2072 (1995)
J. Xu, L.W. Chen, B.A, Li,and H.L. MaPRC77, 014302(2008)
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S.J. LeeA.Z. MekjianPRC79,044323(2009)
S.J. LeeA.Z. MekjianPRC63,044605(2001)
S.J. LeeA.Z. MekjianPRC68,14608(2003)
S.J. LeeA.Z. MekjianPLB580,137(2004)
S.J. LeeA.Z. MekjianPRC77,054612(2008)
Thick: insideThin; outside
Summary
• Surface tension: lower pressure of coexistence binodal surface (toward P=0)
• Coulomb interaction: Shrink binodal region and mechanical and chemical instability region, move LEC to lower than 0.5, cross of curves in y for different P, asymmetric pair of LG at higher , two pairs meet together with lowest P at
• Symmetry energy: for and for , larger symmetry energy make higher pressure and narrower coexistence loop, loops are closer to , tend to restore symmetry of loops
• Value of for LEC is somewhat insensitive to nuclear force, value of pressure is more sensitive
Ey p
Eyy
Ey
LG yy Eyy LG yy Eyy
Ey
Ey
• Mechanical instability loop is inside of chemical instability boundary and tangent at - diffusive chemical transition occurs even in mechanically stable region
• Chemical instability loop is inside of coexistence loop and tangent to it at their maxima in P
• At , all curves coincide in -T plot, phase transition behaves same as one component system
• For , neutron diffusion is important, while proton diffusion for
• Momentum dependent isoscalar makes pressure higher while isovector momentum dependent term makes much lower for given density and y
• Momentum dependent isoscalar makes loops smaller while momentum dependent isovector term makes loops more larger
Ey
Ey
Eyy Eyy
• Momentum dependent isoscalar makes coexistence loop closer to while momentum dependent isovector term makes loop away
• Momentum dependent term lower the height of coexistence loop at proton rich side while it remains similar at neutron rich side
• Momentum dependent isovector term has opposite and larger effect than isoscalar momentum dependent term
• Isovector term make symmetry energy smaller and thus loops become more asymmetric
• For SLy4 left coexistence loop of lower proton fraction is more pronounced than right loop of high proton fraction, isoscalar and isovector have same sign
• SLy4 loop at higher y is narrower in y than loop for SKM(m*=m)
• Symmetry energy has important role in coexistence
Ey
• Surface tension; lower pressure of coexistence binodal surface (to P=0)• Coulomb interaction; shrink binodal loop, cross of chemical potential curves in y for diffe
rent P at near y=0.5, move LEC to smaller yE than 0.5 for symmetric system, asymmetric pair of L-G at higher y > yE, two pairs meet together with lowest P at yE
• Value of yE is somewhat insensitive to nuclear force, pressure is more sensitive• Symmetry energy; Larger y in gas and smaller y in liquid for y > yE, opposite for y < yE • Nonlinear density dependence of symmetry energy• Coulomb shrink chemical & mechanical instability region• Mechanical is inside of chemical and tangent at yE, diffusive chemical transition occurs
even in mechanically stable region, same at yE• Chemical is inside of coexitence and tangent to it at maxima• At yE, peak in chemical instability and binodal surface coincide, • For y.ne.yE In T vs rho, paks for chemical instability and coexistence coincide, but peak
of mrchanical or spinodal instability is below of others• At y = yE, phase transition behaves same as one component system keeping y=yE in bot
h phase• For y < yE, neutron diffusion is important, while proton diffusion for y < yE• Momentum dependence increase pressure at given density• Momentum dependence make smaller boundaries• Reduce height of coexistence loop at proton rich side and remain similar at neutron rich
side, increase lowest pressure of coexistence curve• Largest and smallest y in coexitence loops shifted toward yE
• For SLy4 left coexistence loop of lower proton fraction is more pronounced than right loop of high proton fraction, isoscalar and isovector have same sighn
• For SKM(m*=m) right loop is more pronounced than left loop, isoscalar term raises pressure of loop on neutron rich side while isovector lowers due to opposite sighn of force
• SLy4 loop at higher y is narrower in y than loop for SKM(m*=m), SLy4 has higher symmetry energy
• Higher left loop means liquid and gas can coexist at higher pressurewith more neutron rich gas and lesser rich neutron liquid for left loop
• Narroing of coexistence loop brings yG and yL closer together thereby reducing proton fraction differece in gas and liquid phase
• Momentum dependent isovector term has opposite and larger effect than isoscalar momentum dependent term
• Isovector tem make symmetry energy smaller and thus loops become more adsymmetric
• Pressure for given rho, y, T becomes larger by isoscalar term while it becomes smaller by isovectoer term
• Symmetry energy terms tend to restore dymmetry of loops• Loops for SKM(m*=m) with both isoscalar and isovector terms have smallest sy
mmetry energy, has cut at y=0• Loops for SLy4 with largestsymmetry energy, are closer to its yE than SKM(m*=
m)
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