Isospin study of projectile fragmentation

Content

1 、 Isospin effect and EOS in asymmetry nuclei

2 、 Isotope Yields in projectile ragmentation

3 、 Summary and Outlook

Wendong Tian

Shanghai Institute of Applied Physics, CAS

International Workshop on Nuclear Dynamics 2009 Shanghai

Equation of state of nuclear matter

Dirac-Brueckner Variational+3-body(non-rel.)RMF(NL3) Density-Dependent couplingsChiral Perturbative

Ch.Fuchs, WCI Final Report 2006

Nuclear matter diagram ：Liquid Gas transition

Isospin effect and EOS in asymmetry nucleus

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32

A

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pnI

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Symmetry Energy

2

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BsymB

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B

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symB

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Expansion around

Pressure & compressibilityAsy

-stiff

Asy-soft

Pressure gradient sym

sym KLd

dP

9

1

3

2

Phys.Rep.410(2005)335-466

Asy-su

persti

ff

Isoscaling

Y2/ Y1)exp( ZN

H.S. Xu et al, PRL85(2000) 716M.B. Tsang et al. PRL, 86, 5023 (2001)

Isospin yields of products in 2 isospin different reactions

T

T

p

n

、 and symmetry energy coeficient Csym

2

2

2

1

2

2

2

1

4

4

A

N

A

N

T

C

A

Z

A

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Ca

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sym

Symmetry energy coeficient and chemical potentials

2

2

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V. Baran et al, Phys. Rep. 410, 335 (2005)

Isospin effect in projectile fragmentations

50MeV/u36,40Ar+64Ni

(EMPTY)

(EMPTY)

Isospin yields of projectileSame settings in 2 reactions

Layout of experiment and Detectors, PID :B-TOF-E

B-TOF-E

Shanghai Insitute od Applied Pjysics, CAS, SHanghai

Institute of Modern Physics, CAS, Lanzhou

B=2.32Tm and B=2.36Tm

50MeV/u36Ar+64Ni, PID of PF

B=2.32Tmdp/p=0.6%

50MeV/u36Ar+64Ni, PID of PF after calibration Z%(N-Z)

B=2.32Tmdp/p=0.6%

same rule of event selection

Isotope yields B=2.32Tm dp/p=0.6%

Isotope yields B=2.36Tm dp/p=0.6%

Isotope Yield Ratios and Isoscaling parameters B=2.32Tm,36,40Ar+64Ni

Isotope Yield Ratios and Isoscaling parameters B=2.36Tm,36,40Ar+64Ni

Epax Formula, K. Sümmerer and B. Blank, Phys. Rev. C 61, 034607 (2000).

Theory simulation

Isotope Yields , B=2.32Tm(considering Transmission Rate)

Isotope Yields , B=2.36Tm

Exp Isoscaling parameters Compared with Epax B=2.32Tm,36,40Ar+64Ni

If =4Csym*(Z/A)2/T

Then0.4=0.19*Csym/TCsym/T=2.105

Csym=2.105*T

T1015MeV@50MeV/u

?? New dependence?? Evaporation effect

Theory simulation Simple Code to derive necessary information

Statistical Abration-Ablation model Brohm T and Schmidt K H 1994 Nucl. Phys. A 569 821 Gimard J J and SchmidtK H 1991 Nucl. Phys. A 531 109 Gaimard J-J and Schmidt K-H 1991 Nucl. Phys. A 531 709 Fang D Q et al 2000 Phys. Rev. C 61 044610 Fang D Q et al 2001 Eur. Phys. J. A 10 0381 Cai X Z et al 1998 Phys. Rev. C 58 572

In the SAA model, the nuclear reaction is described as two stages which occur in two distinctly different time scales. The first abrasion stage is the fragmentation reaction which describes the production of the pre-fragment with certain amount of excitation energy through the independent nucleon–nucleon collisions in the overlap zone of the colliding nuclei. The second stage is the evaporation process in which the system reorganizes due to excitation. It de-excites and thermalizes by the cascade evaporation of light particles using the conventional statistical model. The excitation energy for the projectile spectator is estimated by a simple relation of E=13.3<A(b)> MeV where 13.3 is a mean excitationenergy for an abraded nucleon from the initial projectile.

Statistical Abration-Ablation (SAA) model simulation B=2.32Tm,36,40Ar+64Ni

Statistical Abration-Ablation (SAA) model simulation B=2.32Tm,36,40Ar+64Ni

Statistical Abration-Ablation (SAA) model simulation B=2.32Tm,36,40Ar+64Ni

Statistical Abration-Ablation (SAA) model simulation B=2.32Tm,36,40Ar+64Ni

a=5.0

a=10.0

a=13.3

1. Evaporation modify the isotope distribution, leads to the decreasing of in SAA model.

2. Present analysis shows Epax reproduce the experiment better than SAA, but we need one model to reflect the scenario more precisely, so SAA will improved to fit the experimental result, further dynamic model will be tried.

Summmary1.Isotopes yields of the projectile fragmentation from 2 isospin similar reactions were measured and compared in these 2 reactions. Isotope yield ratio were calculated, Isoscaling parameters and are extracted.

2.Isotope yields and isoscaling parameters are compared with those from Epax calculation, Epax can fit the isotope yield, but some discrepency still exist.

3. We simulated the reaction isotope yield by Statistical Abration-Ablation model, and try to fit the experimental result, but not successful yet, SAA simulation is still in progress. Simulation by other code if necessary will be made, and will try to analyze the symmetry energy coeficient Csym from exp and simulation.

Thanks for your attention