F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined...
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Exploring the Isospin Dependence of the Equation of State in Heavy Ion Reactions Betty Tsang NSCL/MSU ACS meeting, San Diego 3/31-4/4, 2001 K(F1) = +61 MeV K(F3) = -69 MeV E(, ) = E(, 0)+E asym () 2 -100 -50 0 50 100 0 0.5 1 1.5 2 Li et al., PRL 78 (1997) 1644 V asy (MeV) / o Neutron Proton F 3 =u F 1 F 2 F 3 u = F 1 =2u 2 /(1+u)
Transcript of F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined...
Exploring the Isospin Dependence of the Equation of
State in Heavy Ion Reactions
Betty Tsang
NSCL/MSU
ACS meeting,
San Diego
3/31-4/4, 2001
K(F1) = +61 MeV
K(F3) = -69 MeV
E(, ) = E(, 0)+Easym() 2
-100
-50
0
50
100
0 0.5 1 1.5 2
Li et al., PRL 78 (1997) 1644
Vas
y (M
eV)
/ o
Neutron
Proton
F3=u
F1F2
F3
u =
F1=2u2/(1+u)
P T
Multifragmentation Scenario
--consistent with mixed phase
Time Sequence
--System expands
-- light particle emitted
-- Fragments form
-- Fragments decouple
Time Dependence
--Initial compression and
energy deposition
-- Expansion
-- Cooling
-- Disassembly and freezeout
Different Approaches
Dynamical (AMD,BNV); Rate equations (EES);
Equilibrium at freeze-out density (BUU-SMM)
10
15
20
25
30
35
40
45
50
0 0.1 0.2 0.3 0.4 0.5
Total Symmetry Energy
ParisBL
AV14
UV14
AV18
S(
) M
eV
(fm-3
)
I.Bo
mb
aci (20
00
)
Dan
ielewicz (2
00
0)
Allowed
region
• No experimental constraints placed on symmetry energy .
• Experiments have placed constraints upon the EOS for symmetric mat ter.
Theoretical predictions of the EOS and symmetry energy
5o
EOS ? ?
0 o
exotics10 km
Relevance to dilute and dense n-rich objects
Neutron Star Structure
Sizes of nuclei with n-
halo and n-skin
Importance of Sequential Decays:
- Primary distributions much wider than secondary
- Dependent on structural information available
- Isotope distribution sensitive to isospin composition of source
Challenges & Opportunities
Current constraints at high density
Future research at CCF will extend the
constraints to low density
Role of density dependent asymmetry term
-Where do the fragments originate?-
• Various models predict different dependence on density dependence of asymmetry term.
– Equilibrium models: fragments originate in interior.
– EES model: fragments emitted from surface.
neutron-richdense region
more symmetricdense region
asy-stiff (F1) asy-soft (F3)
more symmetric emitted particles
neutron-rich emitted particles
Summary
•Density dependence of symmetry energy can be examined experimentally - iso-scaling, mirror nuclear and other experimental signatures
•Conclusions from fragmentation work are model dependent:
–SMM favors 2 dependence of S()–EES favors 2/3 dependence of S()
•Presents lots of challenges or opportunities
-- utilize future rare isotope beam facilities, CCF@ MSU, Riken, Ganil, GSI, RIA-- Need more sophisticated detection equipments
Different EoS for n-stars
Acknowledgements
C.K. Gelbke, T.X. Liu, X.D. Liu, W.G. Lynch, R. Shomin, M.B.
Tsang, W.P. Tan, M.J. Van Goethem, G. Verde, A. Wagner,
H.F. Xi, H.S. Xu, Bao-An Li, B. Davin, Y. Larochelle, R.T. de
Souza, R.J. Charity, L.G. Sobotka , S.R. Souza, R. Donangelo
Bill Friedman
