Dynamics effect and evolution of isoscaling on the Quantum Molecular Dynamics model Wendong TIAN, Yugang MA, Xiangzhou CAI, Jingen CHEN, Jinhui CHEN, Deqing FANG, Wei GUO, Chunwang MA, Guoliang MA, Wenqing SHEN, Kun WANG, Yibin WEI, Tingzhi YAN, Chen ZHONG and Jiaxu ZUO Shanghai Institute of Applied Physics, Chinese Academy of Sciences P. O. Box , Shanghai Massimo Papa, Aldo Bonasera Istituto Nazionale di Fisica Nucleare,Laboratori Nazionali del Sud, Catania,Italy CCAST-----ISOSPIN PHYSICS AND LIQUID GAS PHASE TRANSITION

Outline  Isoscaling  Motivation  CoMD model  Calculation and Discussion  Summary

Isoscaling? If two reactions, 1 and 2, have the same temperature but di ® erent isospin asymmetry, for example, the ratio of a speci ¯ c isotope yields with neutron and proton number N and Z obtained from system 2 and system 1 have been ob- served to exhibit isoscaling, i.e., exponential dependence of the form: where  and  are the scaling parameters and C is anoverall normalization constant, with the convention of that the neutron and proton composition of reaction 2 is more neutron-rich than that of reaction 1. Tsang M B, Friedman W A, Gelbke C K et al 2001 Phys. Rev. Lett

Motivation  Experiment final products, cold, light and few evidence on heavy fragments  Theory Statistical model primary products  final products Dynamical only the hot products, same behavior but different values no dynamical effect shown Mixed of different time emission fragments

CoMd model  Same principle as QMD considering the isospin effect  Some constraints added 1.occupation probability of particle was constrained to f1 in every time step 2. short computation time 3. grounding state consider the isospin degree 4. test the stabability of the ground state to 1000s fm/c  Present simulation 25MeV/A b=1 40 Ca+ 40 Ca, 48 Ca+ 48 Ca Time: 100fm/c ~ 600fm/c with time step =40fm/c

Parameters extracted from the simulation Source Biggest fragment Fragment Only those emitted from source of previous moment  State of the source keep relative stable Temperature light particle spectra (in the rest frame of the source) Neutron, Proton, deutron, Triton, and Alpha

T f =140fm/c

Surface emission: Y S (E RFS )=C·E RFS 1/2 ·exp[-(E RFS -V C )/T] Volumn emission: Y V (E RFS )=C’·E RFS ·exp[-(E RFS -V C )/T] Combination of surface and volumn emission: Y(E RFS )=[C 1 · E RFS 1/2 +C 2 · E RFS ] · exp[-(E RFS -V C )/T] NeutronDeutronAlpha E RFS Temperature T=70fm/c T=220fm/c T=400fm/c

 n,  p Neutron and proton Chemical potential differences between two reactions: = n /T   n = T = p /T   p = T

2 and 2 : Mean value of the parent nuclei

After Evaporation Process Ex=E inc -m-Q E*=factor*Ex factor=0.5 Light fragment: do change too much for the light fragment(a little lower than before evaporation, or say it having same value with T=600fm/c) Heavy fragments: Higher than before evaporation

Summary:  Confirmation of the isoscaling in CoMD dynamical model  Double values obtained of  and  as in our another IQMD model calculation   of the light particles does not change with the evolution time(within the fluctuations), so does the imtermediate fragments(here we only see the light source), but the heavy ones or the residues increase a lot with its mass increasing  No obvious dynamcal behavior of the isoscaling observered, at different evolution time, we find alomost the same , for both light fragmets and heavy source,  values vary much than , and the residue  values change a lot beyond the fluctuation >>>  do no varies with the reaction time,  has a little different  The derived C sym of the light products and IMF, from the observation is differ from the program input, but increase with the mass increase for the heavy residue

More Works: Check of the C sym, the reason causes the Csym deviaration from the input parameter Evaporation decay of the hot products, gemini program will be considered Systimatic simulation of the isoscaling dynamics Isotopic effect from other observations should be analyzed, study the isotopic effect in further The density dependence of isoscaling parameters Excitation energy dependence of the isoscaling parameters