Study of single particle and collective states in nuclei near drip lines

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In this project, the following terms have been studied intensively :1) proton-neutron RPA response function and excited states in skin nuclei.The existence of thick skin has been observed in He-isotopes and A=20 isobars. In these nuclei, one-body field is very different from those of stable nuclei. For example, the radial dependence of the one-body potential is different from that of Woods-Saxon potential and rather close to harmonic oscillator one. In this study, the response of drip line nuclei ^<24>O, ^<48>Ni and ^<60>Ca have been studied especially focusing on the threshold strength.2) Pigmy resonances and Giant resonances in drip line nuclei We have studied dipole states of oxygen-isotopes in large scale shell model calculations. The calculated photoreaction cross sections in ^<16>O and ^<18>O give reasonable agreement with experimental observations both in the low energy region below hω=15 MeV and in the high energy giant resonance region (15 MeV<hω【less than or equal】30 MeV).3) Isospin violation and restoration in thermal compound systemsExplicit relations between the isospin mixing probability, the spreading width Γ^↓_<IAS> of the Isobaric Analog State (IAS) and the statistical decay width Γ_c of the compound nucleus at finite excitation energy, are derived by using the Feshbach projection.