Observation of intermediate bands feeding the positive-parity yrast band in $^{155}$Gd

High-spin states of 155Gd were populated by using the 154Sm(α,3nγ)155Gd reaction at Eα= 33 MeV. γ-γ coincidence, Eγ singles, excitation function, and the DCO ratios were measured. we have identified three intermediate bands with ΔI= 2 feeding the positive yrast band. The bands are interpreted as such candidate bands that are mixed with the negative-parity ground state band. This observation can provide a plausible explanation for unusually large population of the positive-parity yrast band observed in a recent Coulomb excitation.