An investigation of low-lying energy levels of "0 "~Ce, '32'34Nd, and " Pm has been made via P decay, especially of those levels in the E =2+ gamma band in the even-even nuclei. The radioactive parent nuclei were produced by the Mo( Ti,xpyn) and " Sn( 'Si, xpyn) reactions with bombarding energies of 170 to 240 MeV. An isotope separator enabled A=134 mass identification.Level schemes of these five nuclei were constructed from y-y-t coincidence data. The p-decay halflives of the parent nuclei, ' Pr, ' Pr, ' Pm, " Pm, and ' Sm, were determined to be 40+4, 96+18, 8.8+0.8, 23k2, and 9.3+0.8 s, respectively. The suitability of the proton-neutron interaction boson model in describing " Ce, " Ce, '"Nd, and " Nd is supported by the comparison of experimental relative E2 transition probabilities with proton-neutron interaction boson model predictions. ( Si, xnyp) at beam energies of 170, 190, and 220 MeV with targets enriched to 80% in " Sn; (b) Mo( Ti, xnyp) at 250 MeV with targets enriched to 97.4% in Mo; and (c) Mo( Ti, xnyp) at 230 MeV withUNISOR mass separation. Radioactive products were transported by a He-jet system to a continuous thin plastic foil on which they were repeatedly collected and then transported to a y-ray counting station. Two Ge detectors were used, as described in Ref. 18, to obtain y-y-t and X-y-t coincidence spectra as well as singles spectra.