High spin states of some nuclei around the N=Z=28 double closed shell

A spectroscopic study is performed for high spin states of⁵⁵Fe,⁵⁵Co and⁵⁷Ni. To populate the investigated residues with a relevant cross section, the fusion evaporation reactions of³⁰Si(²⁸Si, 2pn)⁵⁵Fe,³⁰Si(²⁸Si, 2np)⁵⁵Co and⁴He(⁵⁴Fe,n)⁵⁷Ni were chosen. To identify the newγ transitions and to build the energy level schemes,γ — γ coincidence techniques together with excitation functions were employed. Angular distributions andγ — γ angular correlations allowed us to assign the spin values of the nuclear states. The previous level scheme of⁵⁵Fe is extended into the region between 6.5–11 MeV of excitation energy, up to spin 27/2, while the yrast decay paths of⁵⁷Ni and⁵⁵Co are reported here for the first time. Experimental data are fairly well reproduced by Glaudemans' shell model calculations.