Collectivity and the role of two-proton and two-neutron excitations in 82Kr

Excited states in ⁸²Kr have been studied in the reaction ⁸⁰Se(α, 2n) by using in-beam γ-ray spectroscopy. Measurements of γγ coincidences, excitation functions, angular distributions and the linear polarization of the γ-rays have been carried out. All together, 38 levels have been identified up to $\text{I = 12}\text{h}\text{?}$ and excitation energies up to 6 MeV. For 23 of these levels the mean lifetime could be determined by Doppler shift and the pulsed-beam γ-timing methods. Most of the levels could be grouped into collective bands according to measured B(E2) values. Two sequences, I^π = 8⁺, 10⁺, 12⁺, are interpreted as rotation-aligned 2q.p. bands built up on $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ protons and neutrons, respectively. Interaction matrix elements between these bands were deduced as V ? 10 keV. Additional states, I^π = (6⁺), 7⁺, 8⁺, indicate coexistence of rotation-aligned and deformation-aligned 2q.p. excitations. An odd-parity ΔI = 1 band is ascribed to proton excitations of the type $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{?}\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$. Several fast M1 transitions with B(M1) = 0.1–1 W.u. have been observe states of equal spin. They are interpreted as being due to configuration mixing.