Systematics of even-even [Formula Presented] 1 nuclei in the [Formula Presented] 80 region: High-spin rotational bands in [Formula Presented]Kr, [Formula Presented]Sr, and [Formula Presented]Zr

High-spin states of [Formula Presented] nuclei were studied with the reactions [Formula Presented]Ni[Formula Presented]Si,[Formula Presented][Formula Presented]Kr, [Formula Presented]Ni[Formula Presented]Si,[Formula Presented][Formula Presented]Sr, and [Formula Presented]Ni[Formula Presented]Si,[Formula Presented][Formula Presented]Zr at 130 MeV beam energy. The Gammasphere array in conjunction with the [Formula Presented] charged-particle detector array Microball was used to detect [Formula Presented] rays in coincidence with evaporated light charged particles. The known [Formula Presented], [Formula Presented] yrast bands were extended to [Formula Presented] at 20 MeV excitation energy. For all three nuclei, a number of positive- and negative-parity sidebands were established; altogether 15 new rotational bands were found. The data are discussed using the pairing-and-deformation self-consistent total Routhian surface (TRS) model: High-spin structures of [Formula Presented]Kr and [Formula Presented]Sr are governed by the shell gaps at large prolate deformation while [Formula Presented]Zr seems to exhibit shape coexistence. Nearly identical bands were established which may be explained as arising from the [Formula Presented] orbits acting as spectators at very elongated shapes. The experimental data in these [Formula Presented] nuclei are in good agreement with predictions of the TRS model using conventional [Formula Presented] like-nucleon pairing correlations.