Comparison of experimental and calculated S-factors of the p-process reaction Sm-144(alpha,gamma)Gd-148
The cross section of the Sm-144(alpha,gamma)Gd-148 reaction has been measured at bombarding energies in the 10.5 - 13.4 MeV range using an activation method based on the off-line alpha-activity measurement of the Gd-148 residual nucleus. The long measuring time of the alpha-decay has required the use of etched track detectors. The resulting cross sections and astrophysical S-factors are compared to new statistical model (Hauser-Feshbach) calculations. The experimental data are strongly overestimated by calculations using global alpha - nucleus optical potentials. The calculated values with potential derived from Sm-144+alpha scattering experiment at E-lab=20 MeV are in good agreement with the experimental results at energies E(cm)greater than or equal to 11.5 MeV, however, largely deviate at lower energies. A fitted Woods-Saxon optical potential, describing remarkably well the experimental data in the whole energy region, clearly indicates a strong energy-dependence of the alpha-nucleus potential.