R. D. Arlt

Multiplet splitting and isomerism in 142Pm and 144Eu

Abstract The level schemes of the doubly odd nuclei 142Pm and 144Eu 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 124Nd or 144Sm. In the final nuclei 142Pm and 144Eu 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 in142Pm and two in 144Eu 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 142Pm and 144Eu have been determined and compared with theoretical values.

Decay of 167Yb (18min) to 167Tm

Abstract The level scheme of the deformed nucleus 167Tm has been investigated in the decay of 167Yb using germanium detectors and a magnetic β-spectrograph. The conversion electron spectrum, single γ-ray spectra and prompt and delayed γ-γ coincidences were measured. A decay scheme is proposed involving 25 excited states in 167Tm and approximately 60 of the more than 100 new transitions. In the low-energy region the first members of the rotational bands 1 2 + [411], 1 2 − [541], 7 2 + [404], 7 2 − [523] and 3 2 + [411] could be identif interpretation of the high-lying levels are discussed on the basis of microscopic theory.