OF NEUTRONS IN THE SPONTANEOUS FISSION OF ~S=Cf

as the detector of the fission fragments of californium. Californium layers with a diameter of 4 mm, a mass of 0.75 ~g (5.1,i0 ~ fissions per sec.) or 0.3 ~g (2,1,105 fissions per sec) were used. The admixed spontaneous fissions resulting from other nuclides of californium and curium were less than 0.2%. The efficiency of recording the fission fragments exceeded 99%. The total timeresolution of the experimental setup amounted to 1.5 nsec. The main uncertainty in the~esolution resulted from the uranium chamber. The time scale was calibrated with an accuracy of~0.1% with the aid of a quartz generator of time intervals. The " zero" of the time was determined with three methods:~from the coincidence of the spectra on the three flight bases, from the simultaneous application of generator pulses to the current-pickup electrodes of the californium and uranium chambers, and from the replacement of the uranium layers in the working chamber by a single uranium iayer with a diameter of l0 mmunder conservation of the capacity. The data obtained with the three methods agreed satisfactorily, / /\ / \ / \ \