Neutron Multiplicities and Yields of Correlated Zr-Ce and Mo-Ba Fragment Paris in Spontaneous Fission ofCf252

High resolution $\gamma -\gamma$ and $\gamma -\gamma -\gamma$ coincidences in the spontaneous fission of ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$ were measured. Relative yields and neutron multiplicities from zero up to 10 were extracted directly for the first time in fission for the Zr-Ce and Mo-Ba correlated fragment pairs. The 0, 8, and the new 10 neutron emission yields for Mo-Ba are significantly larger than those reported previously for total ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$ spontaneous fission. Our results demonstrate that the use of this high resolution $\gamma -\gamma -\gamma$ coincidence technique can provide important, previously inaccessible data on fission.