Investigations of the level scheme of ¹⁴⁴Gd and lifetimes in the quadrupole bands

Abstract.

For a level scheme investigation of ¹⁴⁴Gd an experiment with the $\gamma$-spectrometer EUROBALL III has been carried out and lifetimes have been measured with the $\gamma$-spectrometer GASP using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the ¹⁰⁰Mo(⁴⁸Ti,4n) reaction at 215 MeV and the ¹¹⁴Cd(³⁶S,6n) reaction at E = 182 MeV, respectively. The known quadrupole band has been modified and a new one has been established. Reduced E2 transition probabilities B(E2) were determined for seven members of these quadrupole bands. They show values between $\approx 60$ and 130 W.u. and this considerable enhancement gives evidence for a significant nuclear deformation. A $(\pi h_{11/2})^2 \otimes (\nu h_{11/2})^{-2}$ configuration may be assigned to one of the quadrupole bands according to total Routhian surface calculations. The spin dependence of the B(E2) values has been explained by IBM calculations involving high-spin quasiparticle excitations.