Second order phase transitions from octupole-nondeformed to octupole-deformed shape in the alternating parity bands of nuclei around 240Pu based on data

摘要

Background: Shape phase transitions in finite quantal systems are very interesting phenomena of general physicalninterest. There is a very restricted number of the examples of nuclei demonstrating this phenomenon.nPurpose: Based on experimental excitation spectra, there is a second order phase transition in the alternatingnparity bands of some actinide nuclei.nMethod: The mathematical techniques of supersymmetric quantum mechanics, two-center octupole wavenfunctions ansatz, and the Landau theory of phase transitions are used to analyze the experimental data onnalternating parity bands.nResults: The potential energy of the octupole collective motion is determined and analyzed for all observednvalues of the angular momentum of the alternating parity band states in 232Th, 238U, and 240Pu.nConclusion: It is shown that as a function of increasing angular momentum there is a second order phasentransition from the octupole-nondeformed to the octupole-deformed shape in the considered nuclei.