LNS LNS - - Catania Catania , NIPNE , NIPNE - - HH HH Bucharest Bucharest , INFN and , INFN and Phys Phys . . Dept Dept . Catania, . Catania, INFN and INFN and Phys.Dept. Phys.Dept. Napoli, INFN and Napoli, INFN and Phys.Dept. Phys.Dept. Padova, INFN and Padova, INFN and Phys.Dept. Phys.Dept. Milano Milano … … and and with with the the contribution contribution of a of a very very lively lively Etna mountain! Etna mountain! From the Phys.Dept. Jan.2002 Etna Double-Face, Aug. 2007 PROMPT DIPOLE RADIATION PROMPT DIPOLE RADIATION PEOPLE: PEOPLE: Theory Theory : : V.Baran V.Baran , M.Colonna, M.Di Toro, , M.Colonna, M.Di Toro, C.Rizzo C.Rizzo Experiment Experiment : : D.Pierroutsakou D.Pierroutsakou , , B.Martin B.Martin … … F.Camera F.Camera , , A.Bracco A.Bracco , , A.Corsi A.Corsi , , G.Benzoni G.Benzoni … … C.Signorini C.Signorini , , M.Mazzocco M.Mazzocco … … D D . . Santonocito Santonocito and MEDEA and MEDEA Collab Collab . .
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LNSLNS--CataniaCatania, NIPNE, NIPNE--HH HH BucharestBucharest, INFN and , INFN and PhysPhys. . DeptDept. Catania, . Catania, INFN and INFN and Phys.Dept.Phys.Dept. Napoli, INFN and Napoli, INFN and Phys.Dept.Phys.Dept. Padova, INFN and Padova, INFN and Phys.Dept.Phys.Dept. Milano Milano
…… and and withwith the the contributioncontribution of a of a veryvery livelylively Etna mountain!Etna mountain!
From the Phys.Dept. Jan.2002 Etna Double-Face, Aug. 2007
2. Probing the Symmetry Energy at Sub-Saturation Density
- The “Monster” Prompt Dipole with 132Sn Exotic Beams.
ReactionsReactions havehave beenbeen simulatedsimulated byby consideringconsidering a a stochasticstochastic extensionextension of of microscopicmicroscopic trasporttrasport equationequation BNV, BNV, followingfollowing a a testtest--particleparticle evolutionevolution: : ••VLASOV + NNVLASOV + NN--COLLISIONS and PAULI CORRELATIONS :COLLISIONS and PAULI CORRELATIONS :
( )0 0
U A Bσ
ρ ρρρ ρ
⎛ ⎞ ⎛ ⎞= +⎜ ⎟ ⎜ ⎟
⎝ ⎠ ⎝ ⎠
••SOFT: A = SOFT: A = --358,1MeV; B = 304,8MeV; 358,1MeV; B = 304,8MeV; σσ = 7/6 = 7/6 →→ K=K=201MeV201MeV••STIFF: A = STIFF: A = --123,6MeV; B = 70,4MeV; 123,6MeV; B = 70,4MeV; σσ = 2 = 2 →→ K=K=377MeV377MeV
EQUATION OF STATE:EQUATION OF STATE:
( ) ( ) ( ) 2, ,0 symEE EI IA A A
ρ ρ ρ= +
( ) ( ) ( ) ( ) ( )3 2
KIN POTsym sym sym FE E E C F uA A A
ε ρρ ρ ρ= + = +
( ) ( ) { } [ ] collcoll IfIhft
tprfdt
tprdf δ+=+∂
∂= ,,,,,
[ ]fUm
ph +=2
2 fwfw −+ −− )1(gain loss
Fluctuations
••SELFSELF--CONSISTEN MEAN FIELD:CONSISTEN MEAN FIELD: SkyrmeSkyrme standard standard parameterizationparameterization
DYNAMICAL DIPOLE: DYNAMICAL DIPOLE: PrePre--equilibriumequilibrium dipoledipole mode in mode in phasephase dinucleardinuclear givegiverise rise toto a a promptprompt γγ--rayray emissionemission whichwhich dependsdepends::•• on on initialinitial dipoledipole moment, ;moment, ;
•• on the on the symmetrysymmetry termterm (< (< ρρ00)), , IsovectorIsovector RestoringRestoring Force Force →→ CentroidCentroid, , YieldYieldNeutronNeutron emissionemission →→ DampingDamping
•• on the on the fusionfusion dynamicsdynamics,, NeckNeck DynamicsDynamics (Mass (Mass AsymmetryAsymmetry))AnisotropyAnisotropyCoolingCooling on the way on the way toto FusionFusion
VS.VS.••COLLETTIVE COLLETTIVE →→ DipoleDipole OscillationsOscillations of the of the DiDi--NuclearNuclear System in System in FusionFusion DynamicsDynamics
DK(t)-D(t) SPIRALS→ denotes the collectivenature of the Oscillations!
FromFrom the time the time evolutionevolution of the of the dipoledipole moment in rmoment in r--space space wewe can can applyapply aaBremsstrahlung approach for a Quantitative estimationsof the Dynamical Dipole
]3232S+S+100100Mo Mo SystemsSystems at 9AMeV at 9AMeV beambeam energyenergy: CENTRALITY DEPENDENCE of the : CENTRALITY DEPENDENCE of the SpectraSpectra
DominantDominant DampingDamping MechanismMechanism: : at higher beam energies we aspect a Quenching of the Prompt Dipole Radiation for two main reasons both due to the increasing importance of hard NN collisions:
ENERGY ENERGY DEPENDENCE of the DEPENDENCE of the SpectraSpectra::IncreasingIncreasing aboveabove the Coulomb the Coulomb BarrierBarrier →→ fasterfaster dinucleusdinucleus formationformation, , butbut ……
RISE AND FALL
• a a largerlarger fast fast nucleonnucleon emissionemission thatthat willwill equilibrate the equilibrate the isospinisospin beforebefore the the collettive collettive dipoledipole startsstarts up;up;• a a largerlarger dampingdamping of the collettive mode due of the collettive mode due toto npnp collisionscollisions..
1616O+O+116116Sn,Sn,6464Ni+Ni+6868ZnZn→→ LNL(LNL(GarfieldGarfield) Milano Group, 2007) Milano Group, 2007
AnAn increaseincrease of the GDR of the GDR γγ--rayrayintensityintensity isis foundfound byby goinggoing towardtoward the the more more chargecharge asymmeticasymmetic system.system.θθγγ-- studystudy of the of the extraextra--yieldyield withwithMEDEAMEDEA
■ 36Ar + 96Zr○ 40Ar + 92Zr
The data are The data are linearizedlinearized byby theoreticalγγ--rayray spectrum of the charge symmetricreaction calculated with the statisticaldecay code CASCADE results withouta CN GDR
DipoleDipole AngularAngular DistributionDistribution of the of the ExtraExtra--YieldYield, (10<E, (10<Eγγ<15 <15 MeVMeV))
B.Martin, D.Pierroutsakou et al., Medea Exp. at LNS-Catania, arXiv:0710.1512[nucl-ex]
)](cos1[)( 220 γγ ϑϑ PaWW +=
vs Beam Axis
A strong A strong dipoledipole--likelike photonphoton angularangulardistributiondistribution hashas beenbeen observedobserved, , withwith the the parameterparameter aa2 2 = = --1, 1, W(W(ƟƟγγ,CM,CM))�� sinsin22ƟƟγγ,CM,CM
a2 = -0.8
a2 = -0.5
Widening: rotation of the PromptDipole Axis vs the Beam Axis
W(W(ƟƟ γγ,CM,CM) ) isis anisotropicanisotropic withwith a a maximummaximum aroundaround 9090°° and and itit isisconsistentconsistent withwith emissionemission fromfrom a a
dipoledipole oscillatingoscillating alongalong the the beambeamaxisaxis. .
ISOSPIN DYNAMICS IN DISSIPATIVE HIC: ISOSPIN DYNAMICS IN DISSIPATIVE HIC:
ISOISO--EOS EOS –– SENSITIVE OBSERVABLESSENSITIVE OBSERVABLES
“Violent“ Collisions of Radioactive Beams
AroundAround normalnormal density: Low density: Low toto Fermi Fermi energiesenergies
-- The The PromptPrompt DipoleDipole RadiationRadiation in in FusionFusion ReactionsReactions::YieldYield, , SpectrumSpectrum, , DampingDamping (Energy (Energy DependenceDependence), ), AngularAngular DistributionDistribution