Effects Of Tensor And Pairing Forces On Structure Of Nuclei With Two-Proton Radioactivity

Two-proton radioactivity is one of exotic phenomenon near the proton drip lines.In the process of two-proton radioactivity,the momentum and angular correlation between two protons include the specific form of the nucleon wave function and the interactions,which is important to study the nuclear structure.So,it has been attracted more attention.However,the physical mechanism of two-proton radioactivity is not completely clearly.In order to deeper understand the physical mechanism of two-proton radioactivity,which need to investigate the nuclear structure due to the stability of atomic nuclei related to the nuclear structure.In recent years,it has been found that the tensor forces has an important influence on the nuclear structure near the drip lines.Therefore,it is necessary to introduce the tensor force as an important physical factor to study the nuclear structure of two-proton emission.We systematically calculated the structure of proton-rich O,Ne,Mg,Si,S,Ar and Ca isotopes with 24 sets of TIJ（I or J=1,2...6）interactions in the framework of Skyrme-Hartree-Fock-Bogoliubov（Skyrme-HFB）theory.Not only discussed the relationship between two-proton structure and two-proton radioactivity,but also study the tensor and pairing forces effect on two-proton radioactivity.The specific content of this thesis as follows:（1）The two-proton halo structure of ¹⁸Mg and ²⁰Si are obvious by analyzing the change radii,the proton density distribution and single-proton spectra with the evolution of the tensor interactions,which find that the two-proton halo related to the nucleon occupancy probability of 2s1/2 states near the Feimi energy level.In addition,the two-proton decay types of ¹⁸Mg and ²⁰Si are determined as“²He”cluster emission because the spectra factor of“²He”cluster enhanced by the two-proton halo and further enhanced the“²He”cluster decay pattern.For ¹²O,¹⁶Ne,²⁴S,³⁰Ar and ³²Ca those nuclei,which found that not only without two-proton halo,but also whose decay types are speculated as the sequential or three-body emissions.And the speculated decay types of ¹²O,¹⁶Ne and ³⁰Ar are consistent with the measurements.（2）By observing the radii,the single-proton and the proton density distribution with the evolution of the tensor interactions,which found that the tensor force has an important influence on the two-proton halo and two-proton radioactivity of¹⁸Mg and²⁰Si.In other words,The size of two-proton halo and spectra factor of two-proton radioactivity enhanced with the growth of tensor parametersαorβand further enhanced the²He cluster decay types.In addition,it is found that the influence byαis stronger than that byβ.Then,taking ²⁰Si as an example,the reason of tensor effect on two-proton halo and two-proton radioactivity are explained by analyzing the proton density distributions,single-proton energy levels and spin-orbit coupling potentials with T1J and TI1 interactions.It is found that the tensor force effect on two-proton halo from the competition between the（35）W₀ and（35）aor（35）bcontributions to the spin-orbit potential.（3）By analyzing the evolution of two-proton decay energy with the tensor interactions,which found that the tensor force has some influence on the two-proton decay energy.After analysis,which found that the original from the competition between（35）W₀ contribution to the spin-orbit energy density and（35）aor（35）bcontribution to the tensor energy density.（4）In order to search for new two-proton emission nuclei in the future,the two-proton radioactivity half-lives of these proton-rich nuclei are predicted.By inputting the decay energy of 24 sets of TIJ interactions to the effective liquid drop model and calculated the two-proton radioactivity half-lives of those proton-rich nuclei.It is found that the half-lives of ¹⁶Ne,²⁴S,³⁰Ar and ³²Ca are sensitively depended on the decay energy because of the decay energy is smaller.Nevertheless,the dependence of the half-lives of¹⁸Mg and²⁰Si on the relatively large decay energy is not so strong.Moreover,the order of magnitude of the two-proton radioactivity half-lives of this two nuclei is determined as about 10^-18s.（5）By studying the effect of volume pairing,mixed pairing and surface pairing on extreme proton-rich nuclei,which found that the form of the pairing force has an important effect on two-proton halo size of ¹⁸Mg and ²⁰Si.In other words,the two-proton halo sizes are enhanced strongly by the surface pairing and further enhanced ²He cluster decay types.In addition,by analyzing the evolution of two-proton decay energy with the pairing force,which found that a strong regularity with the evolution of pairing force are shown except ²⁰Si.The decay energy of ¹⁶Ne,¹⁸Mg and³⁰Ar are decrease and these of²²Si,²⁴S and³²Ca are increase with the pairing enhanced.For ¹⁸Mg and ²⁰Si,the decay energy with the surface pairing are smaller than those with the mixed pairing.As a result,the ²He cluster emission are suppressed by the surface pairing.Moreover,the dependence of half-lives on decay energy is same as the conclusion（4）,and the predicted half-lives of ¹⁸Mg and ²⁰Si are still 10^-18s with the volume pairing and the surface pairing.