F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined...

9
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...

Page 1: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

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)

Page 2: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

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)

Page 3: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

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

Page 4: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

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

Page 5: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

Importance of Sequential Decays:

- Primary distributions much wider than secondary

- Dependent on structural information available

- Isotope distribution sensitive to isospin composition of source

Page 6: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

Challenges & Opportunities

Current constraints at high density

Future research at CCF will extend the

constraints to low density

Page 7: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

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

Page 8: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

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

Page 9: F Betty Tsang NSCL/MSU F3 · Summary •Density dependence of symmetry energy can be examined experimentally -iso-scaling, mirror nuclear and other experimental signatures •Conclusions

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