Fragment Isospin as a Probe of Heavy-Ion

Collisions• Symmetry term of EOS• Equilibration• “Fractionation” – inhomogeneous distribution of

isospin • Source composition• Energy spectra• Dynamics : preequilibrium emission / PLF composition • Statistical breakup: composition of fragments • recent work at TAMU and IU

– Peripheral / mid peripheral events: PLF and MR

Z

N

Johnston,1995

RuZr

RuZr

z ZZ

ZZZR

detdet

detdetdet )(2

Rami, 2000

projectile neutrons

projectile protons

target neutrons

target protons

B.A. Li, 1996

Isospin Equilibration

Martin poster

Isotopic composition of fragments as a signature of parent system

R. Wada, Phys. Rev. Lett. 58, 1829-1832 (1987)

Fe+FeFe+Ni

Ni+FeNi+Ni

Ramakrishnan et al, PRC 57, 1803 (1998)

30MeV/nucleon 58Fe,58Ni + 58Fe, 58NiCarbon fragments

Dempsey et al, PRC 54, 1710(1996)

124,136Xe + 112,124Sn55MeV/nucleon

Ramakrishnan et al, PRC 57, 1803 (1998)

58Fe, 58Ni + 58Fe, 58Ni 30 MeV/nucleon

.

2

42643

643

HeHeHe

HeHeHe

Z

N

Martin, et al PRC (2000)

Projectile fragmentation (with isotopically reconstructed QP)

• Isospin effects the dynamics

• QP with a diversity in isospin

• Possible route to neutron-rich RNB – > G.Souliotis clip

28Si + 112Sn, 124Sn @ 30,50MeV/nucleon

20F,20Ne, 20Na + Au @ 32 MeV/nucleon

45.3 cm

Ring 5 Ring 4Ring 3

Ring 2Ring 1

82.2°

42.5°33° 57°

33.6° 22.6°22.37°

14.28° 14.10°8.84° 8.71°

4.6° 4.5°1.64°

Cs I(T l)

S i (53 m m ) + S i-S tr ip (1 47 m m ) + S i (994 m m )Te le sco pe (5cm x 5 cm )

S i (135 m ) + S i (9 93 m ) + C sI(T l)Te le sco pe (5cm x 5 cm )

S id e v iew o f th e d e te c to r se tu p .

FAUST

FAUST

Keksis poster

Beam <N/Z>

proj

<N/Z>

DIT

<N/Z>

DIT+evap

<N/Z>

exp

20Na .818 .926 .876 .912

20Ne 1 1.06 .953 1

20F 1.22 1.23 1.02 1.07

Neutron richness

Rowland PLF

20F,20Ne, 20Na + Au @ 32 MeV/nucleon

D. Rowland

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.8 0.9 1 1.1 1.2 1.3

(N/Z)proj

t/3H

e

20Na

20F

20Ne

20F+Ag

20F+Au

20Ne+Au

20Na+Au

Distillation of a neutron-rich gas?Projectile fragmentation of 20Na,20Ne,20F at 35 Mev/nucleon

124Sn 124Sn

Veselsky, Phys. Rev. C 62, 064613 (2000).

0.6 0.8 1.0 1.2

0

1

2

3

4

5

6

7

8

9

IMF

LCP

ch particles

(50 MeV/nuc)

Mu

lt

N/Z

0.6 0.8 1.0 1.2

0

1

2

3

4

5

6

7

8

9

IMF

LCP

ch particles

(30 MeV/nuc)

Mu

lt

N/Z

0.50 0.75 1.00 1.25 1.50

0.5

1.0

1.5

2.0

2.5

3.0

N/ZQP

(N/Z)IMF

/(N/Z)LCP

50 Mev/nucl

(N/Z

) IMF/(

N/Z

) LC

P

(N/Z)QP

Both the multiplicity and neutron content of the fragmentation products are dependent on the N/Z of the fragmenting system

Veselsky, Phys. Rev. C 62, 041605 (2000)

28Si + 112Sn; 30 & 50 Mev/nuc projectile fragmentation reactions

PLF : Z=12-15 => second source

Laforest, PRC 59, 2567 (1999)

50 Mev/nuc

PPAC2 Stop T Silicon Telescope:ΔE1, X,Y (Strips)ΔE2, Er

PPAC1 Start T X,Y

Production Target

D1D2

D3

WienFilter

Q1Q2Q3

Q4Q5

Dispersive Image

FinalAchromatic Image

Rotatable ArmReaction Angle: 0-12o (selectable)

MARS Acceptances:Anglular: 9 msrMomentum: 4 %

Rare Isotope Production with MARS

Souliotis Clip

Fragments at mid rapidity

larger fragments from midrapidity(Rapidity Dist. for Z = 2, 3, 4 for different Multiplicity

Bins)

124Xe, 124Sn + 112,124Sn

Toke, PRL 75, 2920 ( 1995)

28MeV/A 209Bi + 136Xe<b> = 12.4 fm

Shetty poster

Rapidity Dist. for 3He,4He,6He for different Multiplicity Bins

Shetty poster

124Xe, 124Sn + 112,124Sn

Elab/A

3He, 4He, 6He Spectra Comparison124Xe, 124Sn + 112,124Sn

Beam

LASSA: 9 telescope Si(IP)-Si(IP)-CsI(Tl)/PD array; 7lab58

114,106 Cd + 92,98 Mo at E/A = 50 MeV

Si-CsI(Tl)/PD; 2.5lab4.5

Miniball/Wall; Fast

plastic/CsI(Tl); 2lab170

LASSA

Reproducing Ramakrishnan

(neutron deficient isotopes dominate at central angles)

Hudan Clip

Perpendicular velocity spectra

Hudan Clip

Fractional yield as function of perpendicular velocity

Hudan Clip

Elab/A

Spectral Comparison for Z = 3 Isotopes(change in slope trend for heaviest

isotope?)124Xe, 124Sn + 112,124Sn

Shetty poster

  isotopic energy spectra (preequilibrium effects)

E. Renshaw, Phys. Rev. C 44, 2618-2624 (1991) J. Brzychczyk, Phys. Rev. C 47, 1553-1562 (1993)

Energy Spectra As a Probe Of Symmetry Potential

B.A. Li, PRL 78, 1544 (1997)

Isotope ratios as function of centrality

H. Xu Phys. Rev. C 65, 061602 (2002)

124,136Xe + 112,124Sn 55MeV/nucleon

Dempsey et al, PRC 54, 1710(1996)

114Cd + 98Mo; 50MeV/nuc

Enhanced neutron richness in central versus peripheral collisions

H. Xu Phys. Rev. C 65, 061602 (2002)

In the spirit of the Gordon Conf…

20F,20Ne, 20Na + Au 32 MeV/nucleon

-0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6-2

0

2

p

d

t

3He

4He

6He

6Li

7Li

8Li

7Be

9Be10Be

10B11B

12B

11C12C13C14C

13N14N15N16N

p

dt

3He

4He

6He

6Li7Li

8Li

7Be

9Be10Be

10B11B12B

11C12C13C14C

13N14N15N16N

p

d

t

3He

4He

6He

6Li

7Li8Li

7Be

9Be

10Be

10B

11B

12B

11C12C13C

14C 13N14N15N

16N

-0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6-8

-6

-4

-2

0

2

4

6

8

m=15.21921b=-2.0641

20F + 197Au

(E

/A)

-0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

m=13.56903b=-1.78458

20F + natAg

(Z/A)

m=1.59837b=-0.32586

(E

/A) 20

F+19

7 Au -

(E

/A) 20

F+na

t Ag (

MeV

)

(Z/A)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.5 1 1.5 2

N/Z

no

rma

lize

d t

ime

Na time

Ne time

F time

all isotopes

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

N/Z

rela

tive

tim

e

R

Summary• Fragment Isospin can tell us about

– Equilibration– Source composition – distribution of isospin

• DIT mechanism can be used to create systems with a diversity of isospin

• Isotopic energy spectra are important to understanding the sources of these fragments

The following people were responsible for bringing you the unpublished data shown

in this presentation…*

• B. Davin, R. Alfaro, H. Xu, L. Beaulieu, Y. Larochelle, T. Lefort, R. Yanez, S. Hudan, A. L. Caraley, R. T. de Souza, T. X. Liu, X. D. Liu, W. G. Lynch, R. Shomin, W. P. Tan, M. B. Tsang, A. Vander Molen, A. Wagner,i H. F. Xi, C. K. Gelbke, R. J. Charity, L. G. Sobotka, A.S. Botvina, D. Rowland, D. Shetty, M. Veselsky, G. Souliotis, E. Martin, A. Keksis, E. Winchester,A. Ruangma G. Charbarian, L. Trache, K. Hagel, T. Keutgen, M. Murray, J.B. Natowitz, L. Qin, R. Wada, M. Cinausero, D. Fabris, E. Fioretto, M. Lunardon, G. Nebbia, G. Prete, V. Rizzi, G. Viesti, J. Cibor, Z. Majka, R. Alfarro, A. Martinez-Davalos, A. Menchaca-Rocha

• DOE, NSF, Welch Foundation

*However they should not be held accountable for the actual presentation