Angular distributions of specific gamma rays emitted in the deexcitation of prompt fission products ofCf252

Angular distributions of specific $\gamma$ rays emitted in the deexcitation of prompt fission products of ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$ were measured with respect to the fission direction. A total of 42 angular distributions were measured, 23 of which were of transitions in even-even fragments. The strong anisotropy ($A_2=0.4\mathrm{}-0.6$) measured for $2^{+}$→ $0^{+}$, $4^{+}$→ $2^{+}$, and $6^{+}$ → $4^{+}$ transitions in ${}_{}{}^{138,140}{}_{}{}^{}\mathrm{Xe}$ and ${}_{}{}^{142,144}{}_{}{}^{}\mathrm{Ba}$ provides direct evidence that the angular momentum of the primary fragments is completely aligned perpendicular to the fission axis. Most of the results are consistent with the results of a statistical calculation. The anisotropies measured for some transitions in even-odd fragments were combined with information of other authors in an attempt to determine spins of low-lying levels in these fragments. Finally, it is shown that about 60% of the anisotropy of the gross unresolved $\gamma$-ray spectrum, measured extensively by other authors, is due to transitions in the ground-state band of even-even fragments.