The Study Of The Property Of Thermal And Ense Nuclear Matter In Intermediate Nergy Heavy-ion Collision

In this thesis, we introduce our study on the properties of the high densityand temperature nuclear matter which produced in intermediate energy heavy ioncollisions. Three main parts are contained in this thesis：the study of radial fowand temperature, nuclear modifcation factor, nuclear medium efect, entropydensity.At frst, We study the coupling between the radial fow and random ther-mal motion. In the framework of the Isospin dependence Quantum MolecularDynamics model, we simulate the Au+Au collisions at1AGeV and extract thespectra of diferent particles. Result indicates that the model can describe the ex-periment data from the FOPI and EOS collaborations. By using the distributionfunction from Blast-Wave model to ft the transverse mass spectra of proton, theradial fow and temperature can be extracted at the thermal freeze out time. Themagnitude of radial fow is decreasing with the collisions changing from centralto peripheral, while the temperature has a slight change. However, the spectracannot be described well at the low transverse momentum region when ftted bythe Boltzmann distribution function. This result demonstrates that the radialfow should be exist in heavy ion collisions.Secondly, we introduce the nuclear modifcation factor into the intermediateenergy heavy ion collisions from ultra-relativistic energy region. In RHIC-STARcollaboration, the suppression of nuclear modifcation factor at high pTregion hasbeen discovered, thus this signature become a important proof of the existingof Quark-Gluon Plasma. Within the IQMD model framework, the spectra ofproton have been extracted, and then the ratio RCPhave been calculated. Bycomparing the result from KaoS experiment, the RCPfrom model can matchthe experimental result very well, which has an increasing trend with pT. In thesystematically study on centralities and beam energy, we fnd that the increasingtrend of RCPbecame weaken with a more peripheral collision and at higher beamenergy. The radial fow and Cronin efect are two main reasons which leading a increasing trend of RCP. The RCPof Ï€ has a diferent trend with proton owingto their diferent dynamics process.To further study the RCP, we try to decoupling the contributions from radialfow and random thermal motion. By removing the efect of radial fow, we obtainthe thermal RCPwhich contain the contribution from thermal motion. It hasa fat shape at low pTregion(pT<0.6GeV/c),and then increasing with high pTregion. This result indicate that the radial fow infuence the increasing of RCPat low pTand the Cronin efect afect on high pTregion.Thirdly, we proceed the study of medium efect in the dense nuclear matter.The in medium nucleon-nucleon cross section(NNCS) will be changed in densenuclear matter and infuence on the RCP. The founding result demonstrate thatthe in medium NNCS has a positive correlation with the radial fow and theincreasing slope of RCP. Thus, the RCPmay be a probe of the magnitude ofin medium NNCS. On the other hand, the Ï€ absorption process(Ï€+Nâ†')has been studied by with or without this channel in IQMD model. After closingthe Ï€ absorption channel, the Ï€ become isotopically emitting and the RCPofÏ€ has no dependence on pT. These results indicate that Ï€ absorption processis a dominant factor in Ï€ dynamics，while the infuence of coulomb efect isvery weak. In addition, we try to study the nuclear shadowing efect with thehigh energy Ï€. The high energy Ï€ are produced by hard decay and directÏ€ production process. At the target rapidity, the ratio(N0/N180) of Ï€ yield inthe projectile side and target side has been calculated. The ratio decrease tolow value (smaller than1) at high pTregion, and thus indicate that the highenergy Ï€ emitting to the projectile side have been suppressed due to the nuclearshadowing efect.