Spectroscopic factors from direct proton capture

Spectroscopic factors derived from direct capture studies are systematically compared to those obtained from transfer reaction experiments and from shell model calculations for the A=16-32 target mass region. The direct proton capture and proton transfer spectroscopic factors are obtained in the present work from a reanalysis of literature data by using the same bound state potential parameters. Our direct capture spectroscopic factors differ significantly from the values originally reported in the literature. The sensitivity of the direct capture cross section to different choices for the scattering potential is explored. We find evidence that spectroscopic factors obtained from direct capture studies are as reliable as those extracted from transfer measurements if the (direct capture) radial scattering wave function is calculated with a zero nuclear scattering potential instead of the common choice of a hard-sphere potential.