Photoprotons from Silicon and Phosphorus

Photoprotons from Si and P produced a 24-MeV betatron have been observed in nuclear emulsions. Fine structures are observed in the energy spectrum of Si, showing a fairly similar shape to the excitation curve of Al ( p , γ) reaction. The appearance of these structures is expected resonating group model and probably the channel coupling theory as well. The distances of the proton peaks in the spectrum are nearly equal to those expected these theories. The type of spectrum of Si is different from that of P, and such difference seems to appear between even and odd Z neighbouring nuclei. The angular distributions for P have large maxima around 90°, but those for Si have not so large maxima and minima. This suggests that the shell structure may have some effects on the photonuclear reactions.