LIGHT NUCLEI EMITTED IN FISSION OF 252CF

Energy spectra and angular distributions have been measured for H1, H2, H3, He4, He6, He8, Li, and Be ions emitted in coincidence with the spontaneous fission of Cf252. The data show that, with the possible exception of H1, all of the particles are strongly peaked at 90°with respect to the major fragments, and are probably released by a common mechanism. Using a point-charge model, with various combinations of starting conditions, we have made trajectory calculations for each type of particle. It was found that reasonable agreement with the measured results could be obtained by using a consistent set of initial conditions: namely, a release time of 0.4×10-21 sec, corresponding to a separation distance of 21.5×10-13 cm for the major fragments, and an average initial energy of 2 MeV for the third particle. Both the angular distribution and the energy spectra of the H1 particles appear to be somewhat anomalous in comparison with the calculations, and several possible reasons for this are discussed. We have also observed for the first time isotopes of boron and carbon from the fission of Cf252, and give limits on the energy and yield of heavier particles. © 1968 The American Physical Society.