High-spin states of the isospin T-z = -1/2 nucleus Ni-55 have been ide
ntified for the first time by means of the reaction Si-28(Ar-36,2 alph
a n) at 143 MeV beam energy. The GAMMASPHERE array together with ancil
lary detectors was used to detect gamma rays in coincidence with evapo
rated light particles. The level scheme of Ni-55 comprising four trans
itions is compared to its mirror partner Co-55 and shell-model calcula
tions in the Sp shell.