Development of a SQUID-type detector and a study on systematics of neutron optical potential in the energy region from 0 to a few MeV.

光学模型是核工程领域中子截面计算中最有效、最实用的模型。该模型用复光学势U（r，E）= V（r，E）+ iW（r，E）描述了中子与原子核在较宽能量范围内的平均相互作用。另一方面，最近的研究表明，由色散理论导出的光学势在很宽的中子能量范围内既能代表中子散射态，又能代表束缚态。色散关系为更精确地计算光学势提供了一种有用的方法。通常情况下，W（r，E）必须在较宽的能量范围内是已知的，才能根据这种关系进行分析。然而，由于小于费米表面能的虚表面势W（r，E）不能直接从实验中得到，所以至今还没有得到很好的研究。我们在大坂大学RCNP用偏振束对几种原子核进行了（d，P）或（p，d）反应实验，并计算了单粒子或空穴态的扩展宽度G。根据G = 2W的关系式计算了相应的W（r，E），并对以前的数据进行了同样的重新分析。在此基础上，建立了中子光学势的虚表面势W（r，E）的计算方法，为进一步研究提供了可行性。

The optical model is the most valid and useful model for neutron cross-section evaluation in the nuclear engineering field. The model describes an averaged interacton between neutrons and nuclei in the wide neutron energy range by using the complex optical potential, U(r, E) = V(r, E) + iW(r, E). Continuing efforts have been devoted to a more precise determination of the neutron optical potential.On the other hand, recent studies have shown that an optical potential derived from the dispersion theory represents both the neutron scattering states and bound states in the wide neutron energy range. The dispersion relation offers a useful method to evaluate optical potential more precisely. Usually W(r, E) must be known in the wide energy range for the analysis based on the relation. So far, however, the imaginary surface potential W(r, E) less than the Fermi-surface energy has not been well investigated because the value is not obtained from experiments directly.From this point of view, in the present work, we have studied the systematics of neutron optical potential. We carried out (d, P) or (p, d) reaction experiments for several nuclei by using polarized beam at RCNP (Osaka University) and evaluated the spreading width, G, of the single particle or hole states. The corresponding W(r, E) was calculated on the basis of the relation G = 2W.Previously obtained data were reanalyzed in the same manner. In addition to this, we made some basic investigation on a new type SSD telescope system for the future experiments related to this subject.From the work in this project, we have established an evaluation method of imaginary surface potential W(r, E) of the neutron optical potential and found the feasibility for further investigations.