Currently,experiments on photonuclear reactions are being vigorously conducted worldwide,achieving significant results,and new photonuclear reaction facilities are continuously being designed,built,and operated.Thus,research on photonuclear reactions is highly important and meaningful.Giant dipole resonance(GDR)plays a dominant role in the photon absorption process of atomic nuclei,and can be described within the small amplitude limit of the time-dependent mean field combined with energy density functional.Typically,the quasiparticle random phase approximation(QRPA)method,an approximation of the time-dependent mean field in the small amplitude limit,is used to replace real-time calculations to study the collective excitation states of atomic nuclei.However,the QRPA method also faces some intractable problems.In recent years,with the advent of supercomputers,time-dependent mean-field calculations have developed.The time-dependent Hartree-Fock+BCS(TDHF+BCS)method consistently includes pairing correlations while keeping the computational resources required at an acceptable level.Our research group has recently developed a self-consistent Skyrme TDHF+BCS model which solves in three-dimensional coordinate space and can describe atomic nuclei of any shape,making it a powerful tool for theoretical research on nuclear dynamics.Previous GDR studies within the mean field framework have mostly involved calculations of the total photon absorption cross-section,lacking a systematic study of photonuclear reactions.Such research can help us gain a deeper understanding of the photonuclear interaction process and reveal richer and more detailed information about the internal structure,energy levels,and dynamic effects of atomic nuclei.In this work,we developed the TDHF+BCS model for photonuclear reaction research,enabling it to calculate the absorption cross-sections and their angular distributions for atomic nuclei under different polarization of light.Calculations were conducted for the axially symmetric deformed nucleus 154Sm.In intrinsic coordinate systems,the angular distribution of absorption cross-sections for different polarizations of light shows deformation effects,allowing for the selective excitation of K=0 and K=1 states through angular distributions.Subsequently,we calculated the absorption cross-sections in the laboratory system coordinate.The calculated total absorption cross-section values match well with experimental results.This work,as the initial step in employing the TDHF+BCS framework as a novel tool for photonuclear reaction research,validates the efficacy of this method for photonuclear reaction studies.It also establishes a foundation for more comprehensive and advanced research in photonuclear reactions based on this model in the future.
photonuclear reactionsmicroscopic nuclear dynamicsabsorption cross sectionangular distribution
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