Fragment angular momenta are deduced from the radiochemically determined independent isomeric yield ratios of the antimony isotopes ${}_{}{}^{126}{}_{}{}^{}$,128,130Sb in the alpha-particle-induced fission of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ at various initial excitation energies (18.3–30.2 MeV) and angular momenta (7.86–13.9ħ). It is found that the fragment angular momenta increase with increasing excitation energy and angular momentum of the fissioning nucleus. Calculations of fragment angular momenta are performed based on the Fermi gas approximation for the fissioning nucleus, taking into account the contribution of fissioning nucleus’ angular momentum into that of the fragment. The calculated values agree reasonably well with the experimental values indicating that the fragment angular momenta increase with the increasing initial excitation energy and angular momentum of the fissioning nucleus, with the former playing the dominant role through increased fragment moment of inertia and temperature.

• Received 15 January 1988

DOI:https://doi.org/10.1103/PhysRevC.38.1787