分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Korea plans to build a new radioactive ion-beam accelerator RAON together with various experimental facilities. In particular, KOBRA (the Korea Broad Acceptance Recoil Spectrometer Apparatus) and LAMPS (the Large-Acceptance Multi-Purpose Spectrometer) will be constructed for the nuclear physics experiments. The primary goal of KOBRA is to study the structure of exotic nuclei near drip lines and various astrophysical processes at low energies. On the other hand, LAMPS will investigate the density dependence of the nuclear symmetry energy in wide beam energy range up to 2 times normal nuclear densities. This paper provides an overview of RAON and the experimental setup for the nuclear physics program.
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: We calculated the nucleon self-energies in iso-spin asymmetric nuclear matter and obtained the nuclear symmetry energy by taking difference of these of neutron and proton. We find that the scalar (vector) self-energy part gives a negative (positive) contribution to the nuclear symmetry energy, consistent with the result from relativistic mean-field theories. Also, we found exact four-quark operator product expansion for nucleon sum rule. Among them, twist-4 matrix elements which can be extracted from deep inelastic scattering experiment constitute an essential part in the origin of the nuclear symmetry energy from QCD. Our result also extends early success of QCD sum rule in the symmetric nuclear matter to the asymmetric nuclear matter.
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: An improved isospin dependent Boltzmann Langevin model, in which the inelastic channels and momentum dependent interactions are incorporated, is used to investigate the high-density behavior of nuclear symmetry energy. By taking several forms of nuclear symmetry energy, we calculate the time evolutions of neutron over proton ratio, multiplicity and /+ ratio, and the kinetic energy and transverse momentum spectra of /+ ratio in the heavy ion collisions at 400A MeV. It is found that the neutron over proton ratio and /+ ratio are very sensitive to the nuclear symmetry energy, and the is more sensitive to the nuclear symmetry energy than the +. A supersoft symmetry energy results in a larger /+ ratio.