Correlated Spins of Complementary Fragment Pairs in the Spontaneous Fission of Cf-252

A study of the gamma-ray decay of low-lying excited states in fragments produced in the spontaneous fission of Cf-252 has revealed a significant correlation between the angles of emission of the 2(1)(+) --> 0(1)(+) transitions of complementary fragment pairs. Calculations of the amount of dealignment that is needed to reproduce the measured a(2) values, and a comparison with the results of previous fragment-gamma angular distribution measurements, suggests that at scission there may be significant population of m not equal 0 substates associated with the projection of the fragment spin vector on the fission axis. Fragments from the spontaneous fission of Cm-248 emit 2(1)(+) --> 0(1)(+) gamma rays that show markedly reduced interfragment correlations, suggesting that either a larger role is played by the relative angular momentum of the fragments, or that the dealignment introduced by the neutron emission and statistical gamma decay to the 2(1)(+) state is larger in Cm-248 than Cf-252 fission. [S0556-2813(99)03412-3].