Abstract

High-spin level schemes of the 142Eu, 143Eu and 144Eu nuclei have been investigated by in-beam γ-ray spectroscopic methods using the NORDBALL Compton-suppressed multi-detector array. The previously known schemes have been extended to considerably higher spin and excitation energy, up to I ≈ 30, Ex ⩾ 9 MeV in 142Eu, I = 752, Ex = 15.6 MeV in 143Eu and I ≈ 40, Ex ⩾ 16 MeV in 144Eu. The level schemes are very complicated, characteristic of spherical or slightly oblate nuclei. Also, long cascades of stretched E2 transitions have been observed in all three nuclei. Plunger and DSAM lifetime results demonstrate high collectivity values up to ∼100 W.u. (up to ∼200 W.u. in 142Eu) in these E2 cascades and they are proposed to represent several crossing collective bands with the nucleus at triaxial shape of β2 ≈ 0.25 and γ ≈ 30°. Low parts of the level schemes have been discussed within the spherical shell model. Below 5.5 MeV excitation in 144Eu and 3.5 MeV in 143Eu practically all the observed levels are interpreted with shell model configurations of respectively two or four, and one or three quasiparticles.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call