Investigation of even–even 220–230Th isotopes within the IBM, IVBM and BM

The properties of 220−230Th isotopes were studied and its energy states calculated. To identify the properties of each isotope, the values of the first excited states E21+ and the ratio of the second excited state to the first excited state R4/2=E41+/E21+ were adopted. The phenomenon of back (or up)-bending, the E-GOS curve, the relationship between successive excited states to those preceding them and the staggering in the difference of energies between the ground state band (GSB) and the negative party band (NPB) states were studied. After identifying the properties of each isotope, the appropriate limit in the interacting boson model IBM-1, the IVBM model and the Bohr and Mottelson model were used to calculate the energy states for each isotope and compared the results with the experimental values. Due to the inaccuracy of some calculations in the models IVBM and BM, an adjustment term was added for each model and recalculated the energy states and the results were improved. The contour plots of the potential energy surface (PES) for 220−230Th isotopes are studied using the simplified form of Interacting Boson Model with an intrinsic coherent state.