Magnetic Rotation In Rubidium-84

High-spin states in Rb-84 have been studied by using the Zn-70(O-18, p3n)Rb-84 reaction at beam energy of 75 MeV. Three regular magnetic dipole bands including strong M1 and weak E2 transitions have been observed in this nucleus which shows the characteristic feature of magnetic rotation. These bands are interpreted in the projected shell model for the first time on the basis of the four-quasiparticle configuration of the type pi(fp)circle times pi(g(9/2)(2))circle times nu(g(9/2)). It is shown that the calculated sequence lies roughly in the same energy range as the experimental one but the interval between neighboring levels is larger than the corresponding experimental value. We believe that a 4-quasiparticle band crossing with the 2-quasiparticle band will depress the energies of the states.