Velocities of Fragment Pairs from U233, U235, and Pu239 Fission

Abstract

Velocities of the fragment pairs from thermal-neutron-induced fission of ${\mathrm{U}}^{233}$, ${\mathrm{U}}^{235}$, and ${\mathrm{Pu}}^{239}$ have been measured by a time-of-flight method. The primary masses and energies of the fragments have been determined from the conservation of mass number and momentum. These results are compared with previous fission-fragment-mass and -energy measurements. A decrease of the total kinetic energy near the symmetric mode is observed, which is in agreement with previous double-ionization-chamber measurements. The intrinsic energy spread for mass-97 fragments was found to be 8.1±1.6% with a 95% confidence interval.