Mid-peripheral collisions : PLF* decayStep by stepFragments from the PLF*Comparison with a model : Classical N-Body DynamicsExperimental setupEvents with one heavy fragment from a PLF*One fragment : Isotropic componentOne fragment : reconstruction of the PLF*One fragment : temperaturesVelocity damping and excitation energyEvents with two fragments from a PLF*Two fragments : anisotropy of PLF* decayTwo fragments : relative velocitiesAsymmetry of the breakup : Sensitivity to vPLF*To summarize…Well-defined PLF* : ZPLF* and vPLF*Opening channelsAsymmetry and Coulomb barrierEnergy in the fragmentsA statistical picture : Viola systematicsEstimation of the temperatureSlide 22A law : energy conservation“Missing” energy : Q value?“Missing” energy : evaporation?Energy conservation : balanceA picture of the processTKE : width of the distributionConversion : Q + Coulomb to TKEConclusions : building a coherent pictureInfluence of the targetRatio of the standard fissionSummary & OutlooksCollaborationSpecials Thanks To …Mid-peripheral collisions : PLF* decayPTTLF*PLF*1 fragmentSylvie Hudan, Indiana UniversityvL > vHforwardvH > vLbackwardMore than 2 fragmentsStep by step1) Correlation Size - Velocity2) Experimental setup3) The simplest case : 1 heavy fragment4) Binary breakups : statistical vs. dynamical5) Summary & OutlookFragments from the PLF*ZMAXZ MAX-1Z MAX-2Z MAX-3«+Hierarchy of the velocity and of the angular distribution of the fragments as a fonction of their charge+»Ta+Au 33 MeV/AINDRA dataINDRA dataJ. Normand, J. Colin and D. CussolJ. Normand, J. Colin and D. CussolComparison with a model :Classical N-Body DynamicsD. Cussol, PRC65, 054614 (2002)«Asinthedata,theheaviestfragmentisthefastestandisalignedalongtheQPvelocity»Experimental setupMiniball/MiniwallBeamLASSA : Mass resolution up to Z=97 lab 58Ring Counter :Si (300 m) – CsI(Tl) (2cm)2.1 lab 4.21 unit Z resolutionMass deduced†114Cd+92Moat50A.MeV Detection of charged particles in 4Projectile48† : Modified EPAX K. Sümmerer et al., Phys. Rev. C42, 2546 (1990)Events with one heavy fragment from a PLF*PLFframeWell-defined emission from the PLF30ZPLF*46One fragment : Isotropic componentPLFframeIsotropic componentOther component(mid-rapidity, …)One fragment : reconstruction of the PLF*Fit of the isotropic componentAt = 90, alpha particles 20% of non-statistical emissionMevap=6.97Zevap=10.6ZPLF+Zevap35+10.646(Zprojectile=48)One fragment : temperaturesData:slopetemperatureSimon:emissiontemperatureSimon* : A = 109 E* 500 MeV J = 0 hbar* : D. Durand, Nucl. Phys. A541, 266 (1992)Lower slope temperature for protons and alpha particlesVelocity damping and excitation energyStrong correlation between the multiplicity of evaporated particlesand the velocity dampingVelocity damping correlated to E* Strong correlation between the slope temperature and the velocity dampingEvents with two fragments from a PLF*PLF*ZHZLvL > vH, forwardZHZLvH > vL , backwardLH*PLFZZZ )f(ZAA*PLFL*PLFHA*PLFLLHH*PLFAvAvAvStatisticalbehavior isotropy vH>vLvL>vHTwo fragments : anisotropy of PLF* decay6NC10 Different charge splitsmore asymmetric split for the backward case Different alignments more alignment for the backward caseB. Davin et al., Phys. Rev. C65, 064614 (2002)Two fragments : relative velocities6NC10 Different relative velocities higher vrel for the backward case Dependence with the size for the backward caseB. Davin et al., Phys. Rev. C65, 064614 (2002)Asymmetry of the breakup :Sensitivity to vPLF*6NC10vprojectile = 9.45 cm/nsMore asymmetric Z distribution for the backward caseHigher asymmetry at high vPLF* (low E*,J)For all vPLF* , asymmetry for the backward case An other degree of freedom?vL>vHvH>vLvPLF*9.28.98.38.6E*,Jx100x20x2x80x10x1B. Davin et al., Phys. Rev. C65, 064614 (2002)To summarize…The forward and backward cases are different :Forward emission is consistent with standard statistical emissionBackward emission is consistent with dynamical decay Different charge split dynamical has higher asymmetryDifferent alignment dynamical is more alignedDifferent relative velocity for the same ZL dynamical has higher vrelDifferent Z distribution for a given (E*,J)Well-defined PLF* : ZPLF* and vPLF*vL>vHvH>vLSame correlation expected if vPLF* and E* correlated PLF*PLF*vvσ More dissipation and fluctuations as ZPLF* decreasesFor a given size, less dissipation for the dynamical casedynamicalstatisticaldynamicalOpening channels Dynamical emission opens at higher vPLF* , i.e. lower E* Up to 10% of the cross-section in the 2 fragment decayvL>vHvH>vL1fragment(x0.1)Asymmetry and Coulomb barrierHigher asymmetry for the dynamical caseCoulomb barrier lowerDynamical case appears at lower E*35ZPLF*39LHLHZZZZηEnergy in the fragmentsMore kinetic energy in the 2 fragments for the dynamical caseFor a given vPLF*, difference of 20-30 MeVA statistical picture : Viola systematicsComparison statistical / Viola At large vPLF*, statistical Viola Deviation for low vPLF* Temperature ?Comparison dynamical / Viola For all vPLF*, dynamical >>Viola More compact shape needed for the dynamical case7.3AAZZ*0.755Viola1/321/3121Estimation of the temperatureT2CoulombTKE Measured Estimated (Viola systematic)Statistical case : vL > vHTemperatures between 0 and 10-12 MeVThese temperatures are consistent with T=7 MeV from the isotopes in LASSA (for 30 ZPLF* 46)To summarize…vPLF* as a good observable : Same correlation (vPLF*)-vPLF* for statistical and dynamical cases Dynamical case appears at higher vPLF* Coulomb barrier effect vPLF* (TKE)dynamical > (TKE)statistical by 20-30 MeVStatistical Viola at high vPLF* and deviation with increasing vPLF*TemperatureDynamical case always underestimated by ViolaA law : energy conservationZHZLPLF*++E* , BEPLF*TKEH , BEHTKEL , BELTKEevap ,
or
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