Multiplet splitting and isomerism in 142Pm and 144Eu

Abstract The level schemes of the doubly odd nuclei 142 Pm and 144 Eu were investigated by means of in-beam spectroscopy. High-resolution single γ-ray spectra, conversion electron spectra, prompt and delayed γ-γ coincidences and angular distributions of the γ-rays were measured in the (d, 2n) reaction and partly also in the (p, n) reaction on targets enriched in 124 Nd or 144 Sm. In the final nuclei 142 Pm and 144 Eu twenty and thirteen levels, respectively, have been found below 1.3 MeV. For most of these levels spin and parity values could unambiguously be attributed on the basis of the various experimental data. From lifetime measurements three levels in 142 Pm and two in 144 Eu were found to be isomeric states. A simple calculation assuming a δ-force for the residual interaction between the odd-proton and the odd-neutron hole gives satisfactory agreement with the experimental level energies. The absolute transition probabilities for nine γ-ray transitions in 142 Pm and 144 Eu have been determined and compared with theoretical values.