The Study Of Photon-Nuclear Reactions Based On Nuclear Reactions Transport Mode

The photonuclear reaction has pure electro-magnetic interaction in compared to the traditional nuclear reaction.The reaction probe is very clean and the energy transfer is high-efficient and thus it can be used as an ideal probe for nuclear physics studies.Basic researches using photonuclear reaction have been applied in many fields,including particle physics,nuclear physics and astrophysics.At the same time,the application prospect of photonuclear reaction is broad,such as the treatment of nuclear waste,high-energy photon medical treatment,etc.There are many important applications for light nuclear reactions under GeV energy and above the ? meson threshold.In nuclear physics,the neutron distribution has always been difficult to be extracted in experiment.The neutron distribution can be obtained via the extraction of the neutron skin with the help of the cross section of?0 produced by the light nuclear photo-absorption.In this energy region,? mesons can be used as an effective probe to study the interactions of nuclei.In addition,the ?meson produced by the process of photo-absorption can provide important information about spontaneous symmetry breaking of QGP matter when the hadron is formed through the restoration of the chiral symmetry.Therefore,it is important to study the photonuclear reactions in the region.One of the present thesis work was based on the IQMD model and add the photon absorption branches.The model based on the IQMD with photon channel was established in the intermediate energy region(200-700MeV)for photo-absorption process.The model results are compared with the experimental data and the consistence was found.The results are also compared with the GiBUU model and it is also found to be consistent.It shows that the process of photonuclear reaction in this energy region has little model dependence.Compared with GiBUU model,QMD provides a good description of nuclear fragmentation.Thus,in the future research,it can be used as an effective tool of studying the process of photo-disintegration.The study of quasi-deuteron photo-absorption process has been carried out forquite a long time.The photon from deuterium absorption in the backward in the nucleus can be used as a probe to study the inner nuclear structure.Based on the EQMD model,the quasi-deuteron absorption mechanism of photon is added,which can be used to study the photo-absorption process in quasi-deuteron energy region(70-120MeV).By calculating the energy loss and recoil momentum of the light nuclei12 C and16O and compared with the experimental data,in general,the deuteron absorption process under EQMD is validated.The alpha-cluster structure has been one of the most controversial issues in the nuclear structure for a long time.It is generally believed that alpha-clusters can exist as stable structure in the excited state as well as ground state,by given recent theoretical and experimental evidences.The ground state of 16 O,the tetrahedral configuration could be possible while in the excited state,the kite-shaped,square and chain are possible.The excited state of 12 C may be a long chain and a triangle structure and its ground state is a mixture of sphere and triangle.Possible alpha cluster configuration fot these nuclei can be investigated by quasi-deuteron photon-absortion mechanism.In this work,12 C and 16 O configurations are obtained through the cooling process of the EQMD model.Through the information for emission of neutrons and protons after the final interaction of state,and give a significant difference between this cluster configurations.Due to the cluster structure is possibly different in different models,some microscopic models give a superposition of cluster structure such as12 C is very intense.In this case,it will give more complicated quantitative calculation results.