Positive and negative parity states of 226-236Th isotopes

The level scheme of the 226-236Th nuclei is analyzed using the Interacting Boson Model (IBM-1). The ground state band (g. s.-band), beta band (β-band), gamma band (γ-band) have been described in the sd model space. To calculate the negative parity energy levels, the model space is extended to sdf by adding the f-boson (L=3). A sequence of states in energy bands up to 3.5 MeV has been obtained. The decay of negative states below 1 MeV built on an octupole vibration modes is investigated. The transition probabilities in-band and inter-band are calculated using the wave function of the levels. The potential energy surfaces (PES) values have been plotted to describe the nuclear shape. The model calculations are consistent with the available observed results