FRAGMENT FLOWS IN THE FERMI ENERGY REGIME

Zach Kohley

Physics Division, ORNL

NuSym11

Smith College, Northampton, MA

June 7, 2011

OU

TLINE

Fragment Flows and Nuclear Equation of State (nEOS)

• Definition of Transverse Flow

• Motivation/History

• Experiment

• Flow of Light Charged Particles (LCPs, Z<2)

• Flow of Intermediate Mass Fragments (IMFs, Z>3)

• Summary

• Acknowledgements

2

DEFIN

ITION

Directed/Transverse/Sideward Flow

( / )x

red Y mid rapidity

PF MeV c

Y

PLF

TLF

Projectile

Target

Before Collision After Collision

3

MO

TIVA

TION

/ HISTO

RY

Insight into the forces at play from Ebal measurements

Projectile

Target

Before Collision

G.D Westfall, NPA630, 27 (1998)

Central Collisions

Balance Energy a A-1/3

- Attractive Mean-field (A2/3)

- Repulsive NN Collisions (A)

4

MO

TIVA

TION

/ HISTO

RY

Flow measurements and EoS for N=Z nuclear matter

5

Compressibility (K)

P. Danielewicz et al., Science 298, 1592 (2002)

Giant Monopole Resonance

K = 220-260 MeV

Shlomo S., et al. EPJA, 30, 23 (2006).

D.J. Magestro et al., PRC 62, 041603 (2000)

MO

TIVA

TION

/ HISTO

RY

Flow measurements and NN cross section

6

D.J. Magestro et al., PRC 62, 041603 (2000)Westfall et al., PRL 71, (1993)

MO

TIVA

TION

/ HISTO

RY

N/Z effects observed in flow

signatures by Pak et al.

55 MeV/u

R. Pak et al., PRL 78, 1026 (1997).

R. Pak et al., PRL 78, 1022 (1997).

M. Di Toro et al., Prog. Part. Nucl. Phys. 42, 125 (1999).

L. Scalone et al., Phys. Lett. B 461, 9 (1999). B.A. Li et al., Phys. Rep. 464, 113 (2008).

Predictions of N/P flow

and sensitivity to Esym

Predictions for 3He-3H flow surrogate

- 3He > 3H for Asy-Stiff Esym

- 3He=3H for Asy-Soft Esym

7

Isospin dependence of Mean-FieldIsospin-dependent nn-cross sections

MO

TIVA

TION

/ HISTO

RY

8

Yong et al. PRC 2009Guatam et al. PRC 2011

Li et al. J Phys G 2006

Guatam et al. Proc. DAE 2010

Recent Predictions

9

EX

PER

IMEN

T

Beam Energy: 35 MeV/uReactions: 70Zn+70Zn, 64Zn+64Zn, & 64Ni+64Ni

NIMROD – ISIS Array

10

EX

PER

IMEN

T

- 14 Concentric Rings

- 3.6-167 degrees

- Full Silicon Coverage

- Neutron Ball

S. Wuenschel et al., Nucl. Instrum. Methods. A604, 578–583 (2009).

- Isotopic Resolution ~ Z=1-17

- Elemental Resolution Zprojectile

NIMROD – ISIS Array

Beam Energy: 35 MeV/uReactions: 70Zn+70Zn, 64Zn+64Zn, & 64Ni+64Ni

11

EX

PER

IMEN

T(P

ID)

CsI-PMT Pulse Shape Discrimination

p

t

a

Z=6

Z=13

Silicon-CsI DE-E Plot

Si-Si DE-E Plot

CsI(Tl)

PMT

Si

Particle Identification

12

IMP

AC

TP

AR

AM

ETERA

ND

RX

NP

LAN

E

64Ni

Central/violent

peripheral

12

W.K. Wilson et al., Phys. Rev. C 45, 738, (1992).

Azimuthal Correlations Method

Sub-Event Method

LCP

FLO

W(N/Z)sys Dependence

Mass Dependence

Compare to trends observed by Pak et al.

13

Conventionally – Mass and N/Z effects (Westfall et al. and Pak et al.)

Or is it charge of the system?

Kohley et al. Phys. Rev. C 83, 044601 (2011)

LCP

FLO

WIsotopic LCP Flow Trends

p d t 3He a 6He

• Strong Isotopic Trends

• Flow with n-rich

Kohley et al. Phys. Rev. C 83, 044601 (2011)

64Ni + 64Ni

64Zn + 64Zn

70Zn + 70Zn

• Isobaric Effects (A=3)

•Esym(r) prediction

Increase N/Z = Decrease Flow

14

3H –

3HE

FLO

WSensitivity to Esym(r)

15

no Filter

Filter

Stochastic Mean-Field (SMF)

J. Rizzo et al. Nucl. Phys. A806, 79 (2008).

N/Z = 1.13 1.28 1.33

Kohley et al. Phys. Rev. C 83, 044601 (2011)

3H –

3HE

FLO

WSensitivity to Esym(r)

16

no Filter

Filter

Stochastic Mean-Field (SMF)

J. Rizzo et al. Nucl. Phys. A806, 79 (2008).

N/Z = 1.13 1.28 1.33

Kohley et al. Phys. Rev. C 83, 044601 (2011)

3H –

3HE

FLO

WSensitivity to Esym(r)

17

no Filter

Filter

Stochastic Mean-Field (SMF)

J. Rizzo et al. Nucl. Phys. A806, 79 (2008).

N/Z = 1.13 1.28 1.33

Kohley et al. Phys. Rev. C 83, 044601 (2011)

p d t 3He a 6He

MID

RA

PID

ITYE

MISSSIO

N

18

Neck

QP

Theriault et al., PRC 74, 051602 (2006).

Mid-velocity

Statistical

E. Plagnol et al., PRC 61, 014606 (1999).

Kohley et al. Phys. Rev. C 83, 044601 (2011)

neutron

proton

R. Lionti et al., PLB 625, 33 (2005).

Isospin Migration

Movement of neutrons and protons due to density gradients

(not isospin diffusion).

Symmetric Systems!

Increase N/Z = Decrease F/A & Increase Rmid CO

RR

ELATIO

NS

19

Kohley et al. Phys. Rev. C 83, 044601 (2011)

20

IMF T

RA

NSV

ERSE

FLO

W

Mass Dependence Charge Dependence

Flow Effected by:- Attractive Mean-field (A2/3)- Repulsive NN Collisions (A)- Repulsive Coulomb

Westfall et al. PRL 71, 1986 (1993).Kohley et al., Phys. Rev. C 82, 064601 (2010

Rxn-plane defined from all fragments since examining heavy IMFs

21

IMF T

RA

NSV

ERSE

FLO

W

Mass Dependence Charge Dependence

Kohley et al., Phys. Rev. C 82, 064601 (2010

64Zn 70Zn

64Ni

R~1 R~0.0

22

RFLO

WT

RA

NSITIO

N

64Zn 70Zn

64Ni

R=1

R=0

Mass Dependence Charge Dependence

Kohley et al., Phys. Rev. C 82, 064601 (2010)

23

SEN

SITIVI

TYTO

ESYM

(R)

M. Di Toro et al., Prog. Part. Nucl. Phys. 42, 125 (1999).

L. Scalone et al., Phys. Lett. B 461, 9 (1999).

ESYM

(r) P

RED

ICTIO

N

24

SEN

SITIVI

TYTO

ESYM

(R)

Antisymmetrized Molecular Dynamics (AMD)• Total wavefunction is antisymmetrizedand Pauli Principle is respected at all times.• Dynamics stopped t = 300 fm/c and Gemini applied. (AMD-Gemini)• Momentum dependent interaction (Gogny/Gogny-AS).

A. Ono and H. Horiuchi, Prog. Part.

Nucl. Phys. 53, 501, (2004).

Kohley et al., Phys. Rev. C 82, 064601 (2010)

SEN

SITIVITY

OF

IMF F

LOW

TOE

SYMComparison to AMD-GEMINI Model

25

M.B. Tsang et al. PRL. 102, 122701 (2009).M.B. Tsang, Prog.Part.Nucl.Phys.66,400,2011L.W. Chen et al., Phys. Rev. C 82, 024321 (2010)

AMD Stiff (gogny-AS)AMD Soft (gogny)

SMF StiffSMF Soft

25

Usefulness/Importance of Flow Measurements

P. Danielewicz et al., Science (2002) D.J. Magestro et al., (2000)J. Lukasik et al., PLB (2005)

Probe of EoS for asymmetric nuclear matter.

IMF flows

LCP flows (Ex. 3H-3He)

N/P flows

p+/p- flows

Balance energy

Transverse flow&

Elliptic flow

26

See Talks by:

R. Lemmon

S. Santoro and P. Russotto

A.G. Sood

Conclusions:

Investigation of Transverse Flow of LCPs- New isotopic and isobaric trends observed.- Triton-3He flow should provide a sensitive observable to nEOS.

Investigation of IMF Transverse Flow- Observed system mass dependence in more violent collisions and a charge

dependence in peripheral reactions.- Stiff Esym(r) provided best agreement b/w AMD-Gemini and experiment.- Provides additional evidence for constraining Esym(r) with dynamical observable.

Acknowledgments

-Sherry Yennello Research Group - Kris Hagel and Roy Wada

- Theory: M. Colonna, M. Pfabe and A. Bonasera - Staff of TAMU Cyclotron Institute

- Oak Ridge National Lab / HRIBF - NSF and DOE Funding