HIGH-SPIN 3-PARTICLE STATES IN 207BI

High-spin three-particle levels populated in the decay of a 182±6-μsec isomeric state in Bi207 have been studied using the pulsed external beam of the Stockholm 225-cm cyclotron. The isomeric state was produced in the T1205(28-MeV α, 2n)Bi207 reaction. The intensities and energies of the 13 delayed γ transitions observed fit consistently into a level scheme of six excited levels having energies (keV) and spins: 2101.5 (212), 1645.4 (152), 1357.9 (152), 1240.5 (132), 931.8 (132), and 669.5 (112-) Shell-model calculations have been performed showing that the observed levels can be interpreted as resulting from the coupling of the two-neutron-hole states in Pb206 with the odd proton. From the known level structure of Pb206 and the investigation of the n-p interaction in Bi208, the theoretically expected level structure of Bi207 has been calculated. The average energy difference between theoretically and experimentally determined levels is as low as 18 keV, and the agreement of experimental and theoretical transition probabilities is also satisfactory. The spin assignments are confirmed, and all levels except the 212 are found to have odd parity. © 1969 The American Physical Society.