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The dependence of correlations of neutron multiplicity ν and γ -ray multiplicity Mγ in spontaneous fission of 252Cf on fragment mass A* and total kinetic energy (TKE) have been investigated by employing the ratio of Mγ /ν and the form of Mγ (ν). We show for the first time that Mγ and ν have a complex correlation for heavy fragment masses, while there is a positive dependence ofMγ for light fragment masses and for near-symmetric mass splits. The ratio Mγ /ν exhibits strong shell effects for neutron magic number N = 50 and near doubly magic number shell closure at Z = 50 and N = 82. The γ -ray multiplicity Mγ has a maximum for TKE = 165–170 MeV. Above 170 MeV Mγ (TKE) is approximately linear, while it deviates significantly from a linear dependence at lower TKE. The correlation between the average neutron and γ -ray multiplicities can be partly reproduced by model calculations. [ABSTRACT FROM AUTHOR]

Measurements of charge distributions of fragments in the spontaneous fission of 252Cf have been performed using a unique detector setup consisting of a typical grid-ionization chamber coupled with a ΔE-E charged particle telescope. We find that the fragment mass dependency of the kinetic-energy-averaged width of the charge distribution shows a systematically decreasing trend with obvious fluctuations. The variation of the widths of the charge distribution with kinetic energy shows a pan-like shape. This is due to the large number of neutrons emitted at the high excitation energies and cold fragmentation at the low excitation energies. Deviation of the kinetic-energy-averaged most probable charge Zp from the unchanged charge distribution (UCD), ΔZ, as a function of the mass number of primary fragments, A*, changes from negative for mass asymmetric fission to positive near the symmetric fissions. Concerning the kinetic energy dependence of Zp given primary mass number A*, obvious increasing tendencies of Zp with increasing kinetic energy are observed. [ABSTRACT FROM AUTHOR]