Download What is balance energy?

第十四届全国核结构大会
利用不同出射粒子的平衡能量探测对称
能密度依赖
报告人：王永佳
指导老师：李庆峰
湖州师范学院
2012.04 浙江 湖州
Outline
1
Nuclear symmetry energy
Balance energy---depends on particle species
2
UrQMD transport model
3
Isospin dependence of balance energy
4
5
Results
Summary & Conclusion
Nuclear symmetry energy
It is important in both nuclear physics and astrophysics.
It is not well constrained right now.
pot
kin
Esym  Esym
 Esym
 20MeV   0   12MeV   0 

Super soft
IBUU04: Z. Xiao et al.
PRL102.062502
Moderately soft   0.9  0.4
UrQMD: P.Russotto et al.
PLB697.471
Super stiff
LQMD: Zhao-Qing Feng
Gen-Ming Jin
PLB683.140
23
What is balance energy?
Why we study Balance energy?
Detector acceptance and reaction plane dispersion affect
balance energy weakly.
[Ref.] Deniel Joseph Magestro Ph.D Thesis (MSU 2000)
Balance energy depends on particle species, or not?
70-80A MeV
Old Experiment: not highly depends on particle
species
50-60A MeV
Recent Experiment: depends on particle species
[Ref.] EPJA 30. 31-46
Ultra-relativistic Quantum Molecular Dynamics
(UrQMD) model
Soft-EoS with momentum dependence
K=200MeV
Density and momentum dependent NN
elastic cross section
[Ref.] Qingfeng Li et al.
PRC83.044617
Calculations
More than 500, 000 events for each case were calculated.
V1  y0  by  c
3
0
[Ref.] Chenchen Guo et al. Sci China- Phys G: Mech Astron 55(2) 252-259
Time evolution of baryon densities
The inital N/Z and particle species dependent balance energy
N/Z
N/Z
mass
mass
i. Balance energy increases with increasing N/Z.
ii. Balance energy decreases with increasing mass.
N/Z
mass
 The
influence of symmetry potential on balance energy of
free neutrons is strongest of all.
 Banlance
energy of free neutrons from HIC with isotopes.
Reaction-plane contour plots for isospin asymmetry
  ( n   p ) ( n   p )
Reaction-plane contour plots for isospin asymmetry
  ( n   p ) ( n   p )
Reaction-plane contour plots for isospin asymmetry
  ( n   p ) ( n   p )
Summary & Conculsion
Balance energy of light particles emitted
from mass symmetric HICs with isotopes,
isobars and isotones has been studied.
The balance energy of free neutrons is
sensitive to symmetry energy.
The balance energy of free neutrons from
mass symmetric HICs with isotopes can be
taken as a sensitive probe to complementary
constrain symmetry energy.