The Pygmy Dipole Resonance in The Pygmy Dipole Resonance in the neutron rich nucleus the neutron rich nucleus 6868Ni Ni the neutron rich nucleus the neutron rich nucleus Ni Ni

……andand itsits implicationsimplications forfor the the neutronneutron skinskin in in 208Pb208Pb

Angela BraccoAngela Bracco208Pb208Pb

Universita’ di Milano, INFN sez.di MilanoTrento August 2009Trento August 2009Trento, August 2009Trento, August 2009

OUTLINE OUTLINE

Motivation Motivation Mot at on Mot at on

Experiment description Experiment description Experiment description Experiment description

R lt R lt Results Results

Comparison with theory Comparison with theory

Conclusions and perspectives Conclusions and perspectives

Giant Dipole ResonanceGiant Dipole ResonanceCollective oscillation of neutrons against protonsCollective oscillation of neutrons against protons

20

25

30

ptio

n (

a.u.

)N

harg

e

0

5

10

15

20

Pho

toab

sorp

cros

s se

ctio

n

P

age

Tran

siti

on c

hti

es

0

0 20Gamma Energy [MeV]

Ave

rade

nsit

P Di l R

14

16

n u.)

Pygmy Dipole ResonanceCollective (coherently) oscillation of neutron skin

against the core

4

6

8

10

12

Pho

toab

sorp

tion

oss

sect

ion

(a.u

itio

n ch

arge

GDRPDR

0

2

0 20Gamma Energy [MeV]

Pcr

o

N

Ave

rage

Tra

nsi

dens

itie

s

E1 strength shifted

A. Richter NPA 731(2004)59

E1 strength shiftedtowards low energy (centroid energy depends on the thickness of n-skin)

From the pygmy dipole resonanceFrom the pygmy dipole resonance

One can derive:

NuclearNuclear symmetrysymmetry energyenergy

NeutronNeutron skinskinData on neutron rms radius constrain the isospin-

f h E f f lasymmetric part of the Equation of state of nuclear matter

UsefulUseful information information forforUsefulUseful information information forfor

Relation Relation betweenbetween neutronneutron skinskin and and neutronneutron starsstars :both are built on neutron rich nuclear matter so that one-to-one correlations can be drawn

r-process

Features of this modeFeatures of this mode There is a trend of the strength to increase with the proton-to-

t mm t

There is a trend of the strength to increase with the proton-to-

t mm tneutron asymmetryneutron asymmetry

Stable nucleiStable nuclei ⇒photon scattering PhotoabsorptionStable nucleiStable nuclei ⇒photon scattering Photoabsorption

4040Ca Ca 0.025% EWSR0.025% EWSR

4848Ca Ca 0.29% EWSR0.29% EWSR

T Hartmann PRL85(2000)274

photon scattering,Photoabsorption(γ,γ ’),(γ,n)…photon scattering,Photoabsorption(γ,γ ’),(γ,n)…

T. Hartmann PRL85(2000)274

132132Sn Sn 4% EWSR4% EWSR132132Sn Sn 4% EWSR4% EWSR

Exotic nucleiExotic nucleiVirtual photon breakupVirtual photon breakup

4% EWSR4% EWSR4% EWSR4% EWSR124124Sn Sn

LAND experiment LAND experiment

Adrich et al. PRL 95(2005)132501

Search for pygmy strength Search for pygmy strength in in 6868NiNi

n excess n excess vs inert core : vs inert core : oscillation of the oscillation of the

n excess n excess vs inert core : vs inert core : oscillation of the oscillation of the oscillation of the oscillation of the neutron skinneutron skinoscillation of the oscillation of the neutron skinneutron skinDifferent approaches give

similar predictions in terms of

Different approaches give similar predictions in terms of collectivity, strength and line-shapeof the pygmy resonancecollectivity, strength and line-shapeof the pygmy resonance

RMF

14

16RPA

68Ni

TheoreticalTheoreticalpredictionspredictionsTheoreticalTheoreticalpredictionspredictions

68Ni~10 MeV7%

8

10

12

mb

68Ni~10 MeV3-8%

0

2

4

6

+ J Li t l

D. Vretnar et al. NPA 692(2001)496 G. Colo private communications

0 5 10 15 20 25 30 35 40E nergy (M eV )

+ J. Liang et al.,PRC75(2007)

fRPA: 7-8%:

Virtual photon scattering techniqueVirtual photon scattering technique

Peripheral heavy-ion collision on a high Z target at relativistic energies

197Au(68Ni,68Ni*+γ)197Au197Au(68Ni,68Ni*+γ)197Au

high Z target at relativistic energies

Virtual photon excitation and decayand decay

Relativistic Coulomb excitation (v/c ~ 0.8%)

Virtual Photon Virtual Photon Virtual Photon Virtual Photon

150

200

Virtual Photon Virtual Photon spectrum E1spectrum E1Virtual Photon Virtual Photon spectrum E1spectrum E1θ < θmax

50

100a.u.

b b

Virtual photonγ emission

1 10 1000

50

E* (keV)Emax

b > bmin

( )

Virtual photon scattering techniqueVirtual photon scattering techniqueHigh selectivity for dipole excitation !!High selectivity for dipole excitation !!

Virtual photon scattering techniqueVirtual photon scattering techniqueHigh selectivity for dipole excitation !!High selectivity for dipole excitation !!

•• 600 MeV/u 600 MeV/u 6868NiNi + + 197197Au Au •• 600 MeV/u 600 MeV/u 6868NiNi + + 197197Au Au

High selectivity for dipole excitation !!High selectivity for dipole excitation !!High selectivity for dipole excitation !!High selectivity for dipole excitation !!

600 MeV/u 600 MeV/u NiNi + + Au Au (high statistics) (high statistics)

•• 400 MeV/u 400 MeV/u 6868NiNi + + 197197Au Au (small statistics)(small statistics)

600 MeV/u 600 MeV/u NiNi + + Au Au (high statistics) (high statistics)

•• 400 MeV/u 400 MeV/u 6868NiNi + + 197197Au Au (small statistics)(small statistics)

PbO 20816 +

(small statistics)(small statistics)(small statistics)(small statistics)

Virtual photon excitation Virtual photon excitation and decayand decay of of GDR GDR PYGMYPYGMYand decayand decay of of GDR GDR -- PYGMYPYGMY

T.Aumann et al EPJ 26(2005)441At relativistic energies σ for GRCoul ex > nuclear geometrical σ!

At relativistic energies σ for GRCoul ex > nuclear geometrical σ!

γ

GDR Ground state decayGDR Ground state decayb n hin tib n hin ti

Coul-ex > nuclear geometrical σ!Coul-ex > nuclear geometrical σ!

maximum excitationmaximum excitation

Coulex

[Beene et al PRC 41(1990)920]

branching ratiobranching ratio~~ 2% measured on 2% measured on 208208Pb Pb

maximum excitationmaximum excitationenergy (adiabatic cut off)energy (adiabatic cut off)ca. E*max=18.5 MeVca. E*max=18.5 MeV

High resolution High resolution γγ--spectroscopy at the FRS of GSIspectroscopy at the FRS of GSIHigh resolution High resolution γγ--spectroscopy at the FRS of GSIspectroscopy at the FRS of GSI68Ni beam by 68Ni beam by

FRS provides secondary FRS provides secondary FRS provides secondary FRS provides secondary

Ni beam by fragmentation of 86Kr @ 900 MeV/u on Be target (4g/cm2):

Ni beam by fragmentation of 86Kr @ 900 MeV/u on Be target (4g/cm2):

radioactive ion beamsradioactive ion beamsradioactive ion beamsradioactive ion beamson Be target (4g/cm )

1010 ppspill 86Kr, Spill length 6s,period 10 s

on Be target (4g/cm )

1010 ppspill 86Kr, Spill length 6s,period 10 sp g ,pp g ,p

FRSFRSFRSFRS2g/cm2 Au

RISINGRISING

E b ll E b ll 15 Cl t15 Cl t

Coulomb excitation of Coulomb excitation of 6868Ni @ 600 AMeVNi @ 600 AMeV

Euroball Euroball 15 Clusters15 Clustersat 16.5°, 33°, 36° , E th. ~ 100 keV

Hector Hector 8 BaF8 BaF

RISING ARRAYRISING ARRAYRISING ARRAYRISING ARRAY

Hector Hector 8 BaF8 BaF22

at 142° and 88° E th ~ 2 MeV

MiniballMiniball 7 HPGe7 HPGe segmented detectorsMiniballMiniball 7 HPGe7 HPGe segmented detectorsat 46°, 60°, 80°, 90°E th ~ 100 keV

BeamBeam identificationidentification and trackingtracking detectors Before and after the targetBefore and after the target

Calorimeter Calorimeter Calorimeter Calorimeter TelescopeTelescopefor beamfor beam

identificationidentificationidentificationidentificationCATECATE

Position sensitivePosition sensitive4 CsI9 Si4 CsI9 Si

Coulomb excitation of Coulomb excitation of 6868Ni @ 600 AMeVNi @ 600 AMeVOutgoing 68Ni

after the FRSafter the FRS

From fragmentatiom From fragmentatiom 8686Kr at 900 MeV/uKr at 900 MeV/u

E (C

sI) 68Ni

68Ni -1n68Ni -1p

after the FRSafter the FRS

6868NiNi

∆E (Si)EE ∆∆E E EE ∆∆E E

68Ni -1np

f ff f ff 4000%

∆E (Si)EE--∆∆E E telescopestelescopesEE--∆∆E E telescopestelescopes

~ 6 Days of effective beam time6 Days of effective beam time~ 400 GB of data recorded ~ 400 GB of data recorded

2000%

25.00%

30.00%

35.00%

40.00%

~ 35%

~ 11..101088 ‘ good ‘ good 6868Ni eventsNi events ‘ ‘

000%

5.00%

10.00%

15.00%

20.00%

Incoming+Outgoing Incoming+Outgoing 6868NiNiIncoming+Outgoing Incoming+Outgoing 6868NiNi0.00%

66Co 67Ni 68Ni 69Ni 70Cu

Technical Details Importance of a good timing Importance of a good timing

BaF2HPGe MiniBall

FRS

2

CATE1

2

HPGe CLUSTER

FRS CATE13Beam

Start Detector

Target

CNo Gate

BaF

2(lo

g)

Counts H

PG

No GateThe good timing properties The good timing properties allows to distinguish events allows to distinguish events originating originating

The good timing properties The good timing properties allows to distinguish events allows to distinguish events originating originating

Cou

nts B

Ge (lin)1

23

originating originating from interactions occuring from interactions occuring outside the targetoutside the target

originating originating from interactions occuring from interactions occuring outside the targetoutside the target

190 200 210 220 230

t (ns)

2outside the targetoutside the targetoutside the targetoutside the target

Coulomb excitation : 197Au(68Ni@600AMeV,68Ni*)197AuCoulomb excitation : 197Au(68Ni@600AMeV,68Ni*)197Au

40

60ld

[cts

] “Euroball Clusters” Add-Back and DC

GammaGamma--ray spectraray spectraDoppler corrected dataDoppler corrected dataGammaGamma--ray spectraray spectraDoppler corrected dataDoppler corrected data

20

40

HPGe GEANT

HP

Ge-

Yie

Plus response function Plus response function simulated by GEANTsimulated by GEANTPlus response function Plus response function simulated by GEANTsimulated by GEANT

8 10 12 14 16 18 200

H

Eγ [MeV]

simulated by GEANTsimulated by GEANTsimulated by GEANTsimulated by GEANT

Forward anglesForward anglesγ

Forward : EUROBALL Structure @ 11 MeVStructure @ 11 MeVDC

40 68Ni GEANT

eld

[cts

] in allall detectorsfollowing lorentz boost and E1 angular distributionin allall detectors

following lorentz boost and E1 angular distribution

DC

6 8 10 12 14 16 18

20

BaF

2-Yie

6 8 10 12 14 16 18E

γ [MeV]

Backward HECTORBackward anglesBackward angles

Coulomb excitation of the 2Coulomb excitation of the 2+ + state in state in 6868Ni Ni t 600 M V/t 600 M V/

Coulomb excitation of the 2Coulomb excitation of the 2+ + state in state in 6868Ni Ni t 600 M V/t 600 M V/at 600 MeV/uat 600 MeV/uat 600 MeV/uat 600 MeV/u

Consistency check forConsistency check forConsistency check forConsistency check for

E2 in 68Ni

y fy fDoppler correction Doppler correction mass identificationmass identification

y fy fDoppler correction Doppler correction mass identificationmass identification

2034 keV 2034 keV -- 22++

Comparison RISING with GANIL expComparison RISING with GANIL expComparison RISING with GANIL expComparison RISING with GANIL exp

m fm fcross sectioncross sectionm fm fcross sectioncross section

17.8mBarn

RISINGRISING

Comparison RISING with GANIL exp.Comparison RISING with GANIL exp.excitation of the 2excitation of the 2+ + in in 6868NiNiComparison RISING with GANIL exp.Comparison RISING with GANIL exp.excitation of the 2excitation of the 2+ + in in 6868NiNi22+ + 2743 keV ?2743 keV ?

Sorlin et al

GANIL GANIL --exex

1.6 1.8 2 2.2 2.4 2.6 2.8 3

Sorlin et al. Phys. Rev. Lett (2Sorlin et al. Phys. Rev. Lett (2

γγ--raysrays spectrum spectrum ofofBaFBaF2 2 detectors detectors

an excess yield an excess yield due to beam due to beam emission !!emission !!

Statistical emission of Statistical emission of γγ--rays rays from :from :Statistical emission of Statistical emission of γγ--rays rays from :from :Conditions:Conditions:Conditions:Conditions: from :from :

target nuclei (target nuclei (197197Au) Au) beam nuclei (beam nuclei (6868Ni) Ni)

from :from :target nuclei (target nuclei (197197Au) Au) beam nuclei (beam nuclei (6868Ni) Ni)

Conditions:Conditions:• 68Ni-incoming-selection• 68Ni-outgoing-selection• TOF-in prompt

O l h k

Conditions:Conditions:• 68Ni-incoming-selection• 68Ni-outgoing-selection• TOF-in prompt

O l h kfolded with Response Functionfolded with Response Functionincluding Doppler correction! including Doppler correction! folded with Response Functionfolded with Response Functionincluding Doppler correction! including Doppler correction!

• Outgoing angle check• Doppler correction• mg=1• Detector specific (PSA, AddBack)

• Outgoing angle check• Doppler correction• mg=1• Detector specific (PSA, AddBack)

ground state gammaground state gamma--ray decay from a GR state ray decay from a GR state following a Coulomb excitationfollowing a Coulomb excitationgg

The measured γ-ray yield is due to the product The measured γ ray yield is due to the product of 3 terms:Virtual photon N, photoabsorption cross sect, Branching

[… Beene, Bortignon,Bertulani …]

TOTAL Virtual Photon Number

! Coulomb excitation probability 100

1000Integration over

Ω or bis directly proportional to the Photonuclear cross section 1

10N(Eγ,E1)= 2π∫b(n(Eγ,E1))db

Ω or b

section[Eisenberg,Greiner, Bertulani,Alder,Winther,…]

10 10 20 30

Eγ [MeV]

Photo Photo 120

Photo Photo absorption absorption 80

100

a sorpt on a sorpt on cross cross

ii40

60

σ γ[mB

arn] 68Ni

60Ni

sectionsection6 8 10 12 14 16 18 20 22

0

20

σ

PDR+ GDR

6 8 10 12 14 16 18 20 22

Eγ[MeV]

Gamma decay Gamma decay ––Branching ratio and level density Branching ratio and level density Branching ratio and level density Branching ratio and level density

Branching Ratio for Branching Ratio for γγlevel densitylevel density

Two-steps model,direct GR decay ++ the compound states :

< >< >Rγ(Εγ, ρLD)< >

[Beene, et al PLB (1985)] C.N. Gilbreth and Y. Alhassid, private communicationShell model Monte Carlo (SMMC) Y. Alhassid et al. PRL 99, 162504 (2007

(γ n)VPThe measured gamma yield The measured gamma yield for Coulfor Coul--ex ex h i h i

The measured gamma yield The measured gamma yield for Coulfor Coul--ex ex h i h i

100

120

140(γ,n)

100

1000VP

VP and Rγ σ m

has a cross section has a cross section directly proportional directly proportional to the :to the :

has a cross section has a cross section directly proportional directly proportional to the :to the : 40

60

80

1

10

mb

GDR

Photonuclear Photonuclear cross sectioncross sectionPhotonuclear Photonuclear cross sectioncross section

200.1

68Ni@600 MeV/u GDR

b/M

eV]

PDR

virtual photonsvirtual photons1

Ni@600 MeV/u GDR PDR Total

σ/dE

[mb

Gamma branchingGamma branching1

dσ

PDR5%

GDR

0 1

5%

Response FunctionResponse Function 8 10 12 14 16 18 200.1

Eγ [MeV]without pygmy

68/M PDR

Pygmy dipole resonance in Pygmy dipole resonance in 6868Ni Ni P i P i 6868Ni t 11 M VNi t 11 M VP i P i 6868Ni t 11 M VNi t 11 M V

1

68Ni@600 MeV/u GDR PDR Total

σ/dE

[mb/ PDR Pygmy in Pygmy in 6868Ni at 11 MeVNi at 11 MeV

Width ≈ 2 MeV mainly due

Pygmy in Pygmy in 6868Ni at 11 MeVNi at 11 MeV

Width ≈ 2 MeV mainly due 1d

PDR5%

GDRto Doppler Broadening

5 (p/m 1.5) % of the EWSR

to Doppler Broadening

5 (p/m 1.5) % of the EWSR

8 10 12 14 16 18 200.1

(p )

B(E1) = 1 2 eB(E1) = 1 2 e22fmfm22

(p )

B(E1) = 1 2 eB(E1) = 1 2 e22fmfm22E

γ [MeV]

O. Wieland et al., PRL102(2009)092502

B(E1) 1.2 eB(E1) 1.2 e fmfmB(E1) 1.2 eB(E1) 1.2 e fmfm

Next steps :Next steps :Compare strength with Sn dataCompare strength with Sn dataC ith thC ith th

Next steps :Next steps :Compare strength with Sn dataCompare strength with Sn dataC ith thC ith thCompare with theoryCompare with theoryDeduce the Neutron radius Deduce the Neutron radius Deduce Symmetry energy and Deduce Symmetry energy and

Compare with theoryCompare with theoryDeduce the Neutron radius Deduce the Neutron radius Deduce Symmetry energy and Deduce Symmetry energy and Deduce Symmetry energy and Deduce Symmetry energy and Compare with fragmentation resultsCompare with fragmentation resultsDeduce Symmetry energy and Deduce Symmetry energy and Compare with fragmentation resultsCompare with fragmentation results

Compare the strength in Compare the strength in 6868Ni with Sn dataNi with Sn data

Lower value of the Lower value of the B(E1) in B(E1) in 6868Ni as compare Ni as compare to the Sn region to the Sn region

Lower value of the Lower value of the B(E1) in B(E1) in 6868Ni as compare Ni as compare to the Sn region to the Sn region to the Sn region to the Sn region

This is consistent with This is consistent with

to the Sn region to the Sn region

This is consistent with This is consistent with This is consistent with This is consistent with the fact that (Nthe fact that (N--Z)Z)22/A/A2 2 is is smaller smaller

This is consistent with This is consistent with the fact that (Nthe fact that (N--Z)Z)22/A/A2 2 is is smaller smaller 6868NiNi

(N(N--Z)Z)22/A/A2 2 governs the governs the symmetry energy in finite symmetry energy in finite

(N(N--Z)Z)22/A/A2 2 governs the governs the symmetry energy in finite symmetry energy in finite symmetry energy in finite symmetry energy in finite nucleinucleisymmetry energy in finite symmetry energy in finite nucleinuclei

This is the first hint that from the strength of the pygmyThis is the first hint that from the strength of the pygmyone could get information on the symmetry energyone could get information on the symmetry energyThis is the first hint that from the strength of the pygmyThis is the first hint that from the strength of the pygmyone could get information on the symmetry energyone could get information on the symmetry energyg y y gyg y y gyg y y gyg y y gy

Compare strength of pygmy in Compare strength of pygmy in 6868Ni with theoryNi with theory

Measured Analysis RPAM

eV]

SkI2SkI21

σ/dE

[mb/

68Ni

8 10 12 14 16 18 200.1

dσ

E [MeV]

68Ni

Note that the shape and strengh depends on the effective force Note that the shape and strengh depends on the effective force

Eγ[MeV]

on the effect ve force

Calculations of different types are Calculations of different types are available:available:

on the effect ve force

Calculations of different types are Calculations of different types are available:available:

Microscopic Hartree-Fock + random phase approximation

Microscopic Hartree-Fock + random phase approximation

Relativistic Quasi particle Random Phase approximation

Relativistic Quasi particle Random Phase approximation

Correlation between EWSR and Symmetry energyCorrelation between EWSR and Symmetry energy

6868NiNiFrom experimentW

SRW

SR

NiNip

%EW

%EW

L l t f th EL l t f th Eρρ0 0 = saturation density = saturation density

L slope parameter of the EL slope parameter of the Esymsym

E(ρ,δ) = E0(ρ,δ=0) + S(ρ)δ2 + o(δ2)

L slope parameter KL slope parameter Ksymsym curvature parameter at saturation densitycurvature parameter at saturation density

δδ = (= (ρρnn-- ρρpp)/ ()/ (ρρnn+ + ρρpp))

S(ρ) = S0 +L/3 (ρ- ρ0)/ ρ0+ Ksym((ρ- ρ0)/ ρ0)2 + ….

Expansion around density

6868Ni compared with Ni compared with 132132SnSnThe correlation among the The correlation among the The correlation among the EWSR and L

For 68Ni and 132Sn

The correlation among the EWSR and L

For 68Ni and 132SnRR For 68Ni and 3 Sn

L (MeV) is the slope t f th d it

For 68Ni and 3 Sn

L (MeV) is the slope t f th d it

%EW

S%EW

S

parameter of the density expansion of the Symmetry energy

parameter of the density expansion of the Symmetry energy

L(MeV)L(MeV)

SS0 0 and L for and L for 6868Ni Ni and and 132132SnSnSS0 0 and L for and L for 6868Ni Ni and and 132132SnSn

eV)

eV)

3434From the L value deduced one gets the S0 value

0 4 f l

From the L value deduced one gets the S0 value

0 4 f l

SS 00(M

e(M

e 3434

303030< S0<34 from Sn analysis

of ref PRC76(2007)051601

30< S0<34 from Sn analysis

of ref PRC76(2007)051601 L(MeV)L(MeV)3535 8585

Extract the neutron radius for Extract the neutron radius for 6868Ni and Ni and 132132SnSnRR RR f ti f L f f ti f L f 6868NiNi / /6868RRnn--RRp p as a function of L for as a function of L for 6868NiNi RRnn--RRp p = 0.20 +/= 0.20 +/-- 0.020.026868NiNi

132132SnSn RRnn--RRp p = 0.25 +/= 0.25 +/-- 0.0450.045

6868NiNiRRnn--RRp p as a function of L for as a function of L for 132132SnSn

RRnn--RRpp = 0.20 +/= 0.20 +/-- 0.020.02RRnn--RRpp = 0.20 +/= 0.20 +/-- 0.020.02

L(MeV)L(MeV)L(MeV)L(MeV)

132132SSThe analysis of Klimkiewicz for 132Sn data gave RRnn--RRpp = 0.24 +/= 0.24 +/-- 0.04 0.04

The analysis of Klimkiewicz for 132Sn data gave RRnn--RRpp = 0.24 +/= 0.24 +/-- 0.04 0.04 208208PbPb

L(M V)L(M V)

RRnn--RRp p = 0.25 +/= 0.25 +/-- 0.0450.045RRnn--RRp p = 0.25 +/= 0.25 +/-- 0.0450.045nn

ref PRC76(2007)051601ref PRC76(2007)051601 L slope parameter of EL slope parameter of Esymsym

L(MeV)L(MeV)

Extract the neutron radius for Extract the neutron radius for 208208PbPbRR RR f ti f L f f ti f L f 208208PbPbRRnn--RRp p as a function of L for as a function of L for 208208PbPb Use the L value from the

analysis of the xp im nt f 68Niexperiment of 68Ni

208208PbPb

and using the value of L deduced and using the value of L deduced L slope parameter of EL slope parameter of Esymsym

L(MeV)L(MeV)and using the value of L deduced from 68Ni for 208Pb one obtains

RRnn--RRpp = 0.185+/= 0.185+/-- 0.035 for 0.035 for 208208PbPb

and using the value of L deduced from 68Ni for 208Pb one obtains

RRnn--RRpp = 0.185+/= 0.185+/-- 0.035 for 0.035 for 208208PbPbnn ppnn pp

The analysis of Klimkiewicz based on 132S d t f 208PBThe analysis of Klimkiewicz based on 132S d t f 208PB132Sn data gave for 208PBRRnn--RRpp = 0.18 +/= 0.18 +/-- 0.035 for 0.035 for 208208PbPb132Sn data gave for 208PBRRnn--RRpp = 0.18 +/= 0.18 +/-- 0.035 for 0.035 for 208208PbPb

Neutron skin : RNeutron skin : Rnn-- RRp p summary for summary for 132132Sn, Sn, 6868Ni and Ni and 208208PbPb

Lines from fit of Lines from fit of 132132SnSn

Lines from fit of results based on different forces

Lines from fit of results based on different forces

208208PbPb6868NiNifm

)fm

)

on different forces including relativistic calculations

on different forces including relativistic calculations

6868NiNi

--RR p

p (f(f

L from L from 6868NiNi

L(MeV)L(MeV)

RR nn

PRC76(2007) Present analysisPresent analysisPRC76(2007) Present analysisPresent analysisRRnn-- RRp p (fm)(fm)

L(MeV)L(MeV)

PRC76(2007) Present analysisPresent analysis132Sn 0.24 +- 0.04 0.250+-0.045208Pb 0.18+-0.035 0.185+-0.035

PRC76(2007) Present analysisPresent analysis132Sn 0.24 +- 0.04 0.250+-0.045208Pb 0.18+-0.035 0.185+-0.035

nn p p

Pb 0.18 0.035 0.185 0.03568Ni ----------- 0.200+-0.020

Pb 0.18 0.035 0.185 0.03568Ni ----------- 0.200+-0.020

Comparison with heavy ions fragmentation reactionsComparison with heavy ions fragmentation reactionsTwo different analysis and Two different analysis and measured quantities give consistent measured quantities give consistent

t i t t th t !t i t t th t !

Two different analysis and Two different analysis and measured quantities give consistent measured quantities give consistent

t i t t th t !t i t t th t !constraints to the symmetry energy !constraints to the symmetry energy !constraints to the symmetry energy !constraints to the symmetry energy !

Constraints on the Density dependence of the Symmetry Energy

Measurements from collisions I l i 112S d 124S Involving 112Sn and 124Sn with improved quantum molecular dynamics transport modelmodel

M.B. Tsang et al. PRL102(2009)122701

O. WielandO. Wieland , A. Braccoa, G. Benzonia, N. Blasia, S. Brambillaa, F. Cameraa

F.C.L. Crespia, S. Leonia, B. Milliona, R.Nicolinia A. Majb, P. Bednarczykb,cJ. Gręboszb, M. Kmiecikb,

W. Męczyńskib, J. StyczeńbT. Aumannc, A. Banuc, T. Beckc, F. Beckerc, L. CacerescP. Doornenbalc, H. Emlingc, J. Gerlc, H. Geisselc, M. GorskacO. Kavatsyukc, M. Kavatsyukc, I. Kojouharovc , N. KurzcR. Lozevac, N. Saitoc, T. Saitoc, H. Schaffnerc

H J Wollersheimc J Jolied P Reiterd N Warrd G de Angelise A Gadeae D Napolie S Lenzif S LunardifH.J. Wollersheimc, J. Jolied, P. Reiterd, N. Warrd G. de Angelise, A. Gadeae, D. Napolie, S. Lenzif , S. Lunardif

D. Balabanskig, G. Lo Biancog, C. Petracheg, A. Saltarellig, M. Castoldih, A. Zucchiattih, J. Walkeri, A. Bürgerj

aUniversity of Milan and INFN Section of Milan, ItalybInstitute of Nuclear Physics Polish Academy of Sciences Kraków PolandInstitute of Nuclear Physics, Polish Academy of Sciences, Kraków, PolandcGSI, Planckstrasse 1, 64291, Darmstadt, GermanydUniversity of Koeln, GermanyeNational Laboratory of Legnaro, INFN, Italyy g , , yfUniversity of Padova and INFN Section of Padova, ItalygUniversity of Camerino, and INFN Section of Perugia, ItalyhINFN Section of Genova, ItalyiUniversity of Surrey, United KingdomjHISKP, University of Bonn, Nußallee 14–16, 53115 Bonn, Germany

Analysis using theory…….

A. Carbone, P.F. Bortignon, A. Bracco, F. Camera, G. Colò, O. Wieland

Analysis using theory…….

A. Carbone, P.F. Bortignon, A. Bracco, F. Camera, G. Colò, O. Wieland A. Carbone, P.F. Bortignon, A. Bracco, F. Camera, G. Colò, O. Wieland (University of Milano and INFN) A. Carbone, P.F. Bortignon, A. Bracco, F. Camera, G. Colò, O. Wieland (University of Milano and INFN)

ConclusionsConclusionsMeasurement of hi h ener y hi h ener y raysrays from Coulex of 6868Ni at 600 MeV/uNi at 600 MeV/uMeasurement of hi h ener y hi h ener y raysrays from Coulex of 6868Ni at 600 MeV/uNi at 600 MeV/uMeasurement of high energy high energy γγ--raysrays from Coulex of 6868Ni at 600 MeV/u.Ni at 600 MeV/u.

Strength at 11 MeVStrength at 11 MeV has been observed (5% EWSR)

Measurement of high energy high energy γγ--raysrays from Coulex of 6868Ni at 600 MeV/u.Ni at 600 MeV/u.

Strength at 11 MeVStrength at 11 MeV has been observed (5% EWSR)The theory (RMF and RRPA calculations) predicts 4-8% at 9-10MeVAn analysis based on an correlation of the EWSR with the symmetry The theory (RMF and RRPA calculations) predicts 4-8% at 9-10MeVAn analysis based on an correlation of the EWSR with the symmetry

energy L parameter deduced for the available different forces gives

The radius of the neutron skinThe radius of the neutron skin (verified for 208Pb and 132Sn)

energy L parameter deduced for the available different forces gives

The radius of the neutron skinThe radius of the neutron skin (verified for 208Pb and 132Sn)( )

Contraints on the symmetry energy symmetry energy in agreement with heavy ion fragmentation

( )

Contraints on the symmetry energy symmetry energy in agreement with heavy ion fragmentationwith heavy ion fragmentation

The results open new perspectives for other experiments and are very promising for future measurements especially with higher

with heavy ion fragmentation

The results open new perspectives for other experiments and are very promising for future measurements especially with higher very promising for future measurements especially with higher resolutionvery promising for future measurements especially with higher resolution

Thanks for the attention !! Thanks for the attention !! Thanks for the attention !! Thanks for the attention !!