Angular Distribution of Fission Fragments from theYb170Compound Nucleus Excited to 107 MeV

Abstract

The angular distribution of the fission products formed in the reaction of 126-MeV ${\mathrm{C}}^{12}$ ions with ${\mathrm{Gd}}^{158}$ and 137-MeV ${\mathrm{O}}^{16}$ ions with ${\mathrm{Sm}}^{154}$, both of which give ${\mathrm{Yb}}^{170}$ compound nuclei at an excitation of 107 MeV, have been measured. It is found that the angular distribution in the ${\mathrm{C}}^{12}$-ion entrance channel is proportional to $\frac{1}{sin\theta }$ from about 25 to 155° in the center-of-mass system, while the corresponding range is about 15 to 165° for the ${\mathrm{O}}^{16}$-ion entrance channel. The total fission cross sections are 20 ± 2 and 39 ± 4 mb for the two entrance channels, respectively.