【摘要】 本文研究了在中子-核散射中存在的以GR（巨共振）为中间态的反应机制。在特殊情况下(如⁸⁷Sr—中子满壳缺一中子的核),入射中子能量E_n～3MeV时,由GR贡献的非弹截面可达10mb。对于不同的靶核,这种反应机制对非弹截面的贡献,在适当入射中子能量（?）时达到最大值,其中（?）=（?）ω_λτ—S,S为靶核加入射中子形成的核处于基态时的核子分离能,（?）ω_λτ为相应的GR的能量。更多还原

【Abstract】 Virtual excitation of GR in neutron-nucleus seattering is studied for a particular type of unclei. (Nuclei with a hole in a neutron close shell such as ⁸⁷Sr.) It is found that for such type of nuclei the contribution to inelastic scattering is important even when the incident neutron energy is arround 3 MeV in contrast to the case of close shell target nuclei as investigated by V. Geramb.For an incident neutron energy E_n～3MeV, besides the compound nucleus formation, the following two processes also contribute to the inelastic cross section:The intermediate states involving the virtual excitation of the GR’s are treated phenomenologically as well as microscopically. In the former case they are taken to be simple resonances with definite widths. For resonable values of parameters C_λτ (or （a_o）_λτ), Γ_λτ and Δ, the contribution to the inelastic cross section due to GR’s is about 10 mb. In the latter case, the GR’s are taken to be a collection of 1p1h RPA phonons each with definite width. Here the coupling constant x between phonon and nucleons is taken to be 0.00337 MeV in accordance with the value given by A. Bohr, Again the contribution to the inelastic cross section is about 10 mb. One can therefore expect that this reaction mechanism is present in a variety of reactions besides （n, n’） with sizable cross section. The energy of the incident partiele （?） at which the effect of the GR’s is expected to be strongest depends on the structure of the target nucleus. For （n, n’）. E～hω_λτ-S_n where Sn is the neutron seperation energy of the target plus one neutron nuclei in the ground state and hω_λτ is energy of GR with isospin τ and multipolarity λ.It is needed further to investigate to what extent the phenomenological treatment of the intermediate states by representing the GR as a single resonance phonon will be valid and what best values for the width should be taken.This has somthing to do with the nature of the GR’s when treated as oscillations in the quantum fluid, the nuclear matter of finite extension.更多还原