yields

fission fragments

neutron-induced fission

Physical review

Pre-neutron-emission fragment-mass and total-kinetic-energy distributions and the mass-energy correlations in the spontaneous-fission decay of 2.30-sec $^{252}\mathrm{No}$ have been deduced from measured energies of coincident fragment pairs using silicon surface-barrier detectors. The $^{252}\mathrm{No}$ for these measurements was produced in the $^{241}\mathrm{Am}(^{15}\mathrm{N}, 4n)$ reaction and deposited on 40-\ensuremath{\mu}g ${\mathrm{cm}}^{\ensuremath{-}2}$ carbon foils using a He-jet technique. From an analysis of 154 correlated fission events, the average pre-neutron-emission total-kinetic energy, $〈\mathrm{TKE}〉$, was found to be 202.4\ifmmode\pm\else\textpm\fi{}1.2 MeV. The mass distribution is decidedly asymmetric, similar to that observed for $^{252}\mathrm{Cf}$ spontaneous fission, although a maximum in the $〈\mathrm{TKE}〉$ curve as a function of fragment mass occurs for near-symmetric mass divisions as it does for the heavier isotopes of fermium. The measured spontaneous-fission-decay branching fraction for $^{252}\mathrm{No}$ is 26.9\ifmmode\pm\else\textpm\fi{}1.9% and the measured total half-life is 2.30\ifmmode\pm\else\textpm\fi{}0.22 sec. The measured and deduced fission char\`acteristics for $^{252}\mathrm{No}$ are compared with those for the Cm, Cf, and Fm nuclides as well as with recent theoretical predictions.RADIOACTIVITY, FISSION $^{252}\mathrm{No}(\ensuremath{\alpha}, \mathrm{sf})$ measured fragment-fragment coin $E$, ${T}_{\frac{1}{2}}$, $E\ensuremath{\alpha}$, $\frac{\ensuremath{\alpha}}{\mathrm{sf}}$, $\ensuremath{\sigma}$ for $^{241}\mathrm{Am}(^{15}\mathrm{N}, 4n)$ reaction; deduced pre-neutron fragment masses, energies, and total kinetic $E$ distribution. Enriched target.

Fragment-mass and kinetic-energy distributions from the spontaneous fission ofNo252