Determination of nuclear structure parameters in medium mass nuclei by gamma spectroscopy in heavy ion reactions.Contributions to the study of nuclei in the mass region A ≅ 70

The extensive experimental and theoretical work on the structure of nuclei near A=70 has revealed large deformations, rapid changes in structure as a function of particle number and shape coexistence at low spins. The thesis presents some contributions to the study of high-spin states in some neutron deficient even-even, odd and odd-odd nuclei belonging to the A=60-80 mass region: 65 Zn, 66Ga, 67 Ga, 70As, 72 As, 72 Se. The high-spin states were populated using 12 C, 14 N and 16 O beams on 56 Fe, 59 Co and 58 Ni targets. In Chapter 1 the results of recoil-distance measurements in 72 Se for 2+, 4+ and 6+ states are presented; the measured reduced transition probabilities B(E2) are compared with calculations using a simple coexistence model. The design and performances of a target chamber for recoil distance measurements are also presented. In chapter 2 the results of complex gamma-ray spectroscopic investigations (cross bombardments, excitation functions, angular distributions, gamma-gamma coincidences, lifetime measurements, and linear polarization measurements) on 70 As are presented. As a result, a complex level scheme with many new spin and parity assignments was constructed for 70 As. Chapter 3 is devoted to presentation of magnetic moment measurements in 65 Zn, 66Ga, 67 Ga and 70 As using time-integral perturbed angular distributions. Chapter 4 presents excitation functions, gamma-gamma coincidences and lifetime measurements in 72 As. A level scheme was constructed and some discrepancies existing in the literature on the level scheme were solved. Finally, some conclusions on the studied nuclei are presented. (author) 55 figs., 15 tabs., 67 refs