Fine structure in α decay of even-even nuclei using a finite-range nucleon-nucleon interaction

A systematic study on alpha-decay fine structure is presented for even-even nuclei in the range 78 <= Z <= 102. The penetration probability is obtained from the WKB approximation in combination with the Bohr-Sommerfeld quantization condition. The potential barrier is numerically constructed in the well-established double-folding model for both Coulomb and nuclear potentials. A realistic M3Y interaction, based on the G-matrix elements of the Paris NN potential, has been used in the folding calculation. The local approximation for the nondiagonal one-body density matrix in the calculation of the exchange potential was included by using the harmonic oscillator representation of the nondiagonal density matrix of the a particle. The computed partial half-lives and branching ratios are compared with the recent experimental data and they are in good agreement.