Nuclear structure studies in the medium mass (A /approximately equals/ 70) region

The in-beam /gamma/-ray studies on several nuclei in A /approximately equals/ 70 region, have revealed highly collective band structures of the following types: 1) ground state band, 2) one or two even spin positive parity bands with 8/sup +/ as band head, 3) odd and even spin negative parity bands, 4) /DELTA/J.1 even parity bands with 2/sup +/ as band heads, 5) deformed bands built on the first excited O/sup +/ states. Not all these types of bands have been observed in all of the nuclei in this mass region. The even spin positive parity bands with 8/sup +/ as band head and the negative parity bands can be understood in terms of rotational alignment model. The Interacting Boson Model calculations reproduce the negative parity bands and the /DELTA/J.1 even parity bands with 2/sup +/ as band head. 28 refs