Study Of α Clusters Properties Of ¹²C,¹⁶O Excited State In Hot Nuclear Matter

The heavy ion nuclear reaction in the Fermi energy region undergoes the process of nuclear compression,expansion,particle emission,and multifragmentations,forming the high-temperature and high-density extreme conditions of the thermonuclear material environment,which can be used for the study of atomic clusters in hot nuclear matter.Based on the 35AMe V ^70（64）Zn(⁶⁴Ni)+^70（64）Zn(⁶⁴Ni)and ⁴⁰Ca+⁴⁰Ca heavy ion collision experiments conducted at the NIMROD full solid angle detection system at the accelerator cyclotron institute of Texas A&M university,the 3αs,and 4αs associated events are precisely selected.The invariant mass spectra ofαconjugate nuclei are reconstructed and the excited energy levels are confirmed.By comparing the experimental results with the simulation results of quantum molecular dynamics models AMD and Co MD,the physical mechanism of cluster structure is studied deeply.The research is mainly carried out in the following two aspects:Firstly,the ¹²C Hoyle state and Efimov state are reconstructed by using the energy and position information of the finalαparticles in ^70（64）Zn(⁶⁴Ni)+^70（64）Zn(⁶⁴Ni)data.The ¹²C excited energy levels are obtained:7.458Me V（Efimov state）,7.654Me V（Hoyle state）.The excited energy level E^*=14.72Me V is obtained by reconstructing ¹⁶O by the method of the relative kinetic energy of 4αs particles.The 3αs events of the ⁴⁰Ca+⁴⁰Ca system are analyzed by using the same method.It is found that the reconstructed excitation energy for the minimum and intermediate relative kinetic energy E_ij^Min=E_ij^Mid=0.192Me V±δE?3 Me V are in agreement with the Hoyle state of ¹²C within the error range.Secondly,the ¹²C cluster structure is studied theoretically using AMD and Co MD models.The nuclear reaction kinetics of ^70（64）Zn(⁶⁴Ni)+^70（64）Zn(⁶⁴Ni)and ⁴⁰Ca+⁴⁰Ca at 35 A Me V were calculated systematically.The charge（Z）distribution and mass（A）distribution agree well with the available experimental data.When using the relative kinetic energy method to analyze the 3αs event,during the reconstruction of the ¹²C invariant mass spectrum,due to the high binding energy of ⁸Be in the model,it could not decay into 2αs,resulting in the formant and background could not be distinguished.In this paper,theαcluster structure of the ¹²C,¹⁶O Hoyle state and their nearby excited states is discussed in depth.The theoretical calculation is made and the possibility of the existence of Efimov states near the Hoyle state is given.This will provide a more effective experimental methods and theoretical basis for studyingαcluster structures in the properties ofαcluster structures in moreα-conjugated light nuclei.