Neutron correlations in spontaneous fission of 252Cf

The variance and covariance of the neutron distributions in fission fragments of ²⁵²Cf have been measured as a function of the fragment mass and total kinetic energy. The neutrons were detected by a time-of-flight technique. The covariance results indicate that there is no change in the degree of viscosity in the transition of the fissioning nucleus to the scission point as a function of the total excitation energy. There are some discrepancies between various features of the neutron evaporation cascade determined in our experiment and results of standard evaporation calculations. No simple explanation of these discrepancies is offered. [RADIOACTIVITY, FISSION ²⁵²Cf(sf); measured variance and covariance of γ(A,E) of the two fragments.]