Toward Understanding of the Nuclear Force Via Detailed Spectroscopy of ²⁰⁸Bi and Development of New Techniques for Studies of Neutron Rich Exotic Nuclei: Spectroscopy of ⁷He.

This thesis is an experimental study of the nuclear force. In the first part of the thesis the single particle structure of ²⁰⁸Bi is studied via the γ - γ coincidence technique. This experimental data provides information about the residual particle-hole interaction in the Lead region. In the second part of the thesis the structure of ⁷He is studied. The experimental study of ⁷He was motivated by experimental evidence for reduction of the spin-orbit force in the above nucleus. To study the ⁷He structure two new experimental techniques were developed. The new data obtained with these techniques showed that there is no reduction of the spin orbit force in ⁷He. It is shown that the developed methods can be used to study other exotic neutron rich nuclei. The techniques are described in details in this work and future prospectives are given.