MULTIPLICITY AND ENERGY OF NEUTRONS FROM U-235(N(TH),F) FISSION FRAGMENTS

The correlation between fission fragments and prompt neutrons from the reaction U-235(n(th),f) was measured with improved accuracy. The resu lts determined the neutron multiplicity and emission energy as a funct ion of fragment mass and/or total kinetic energy. The average multipli city as a function of fragment mass followed a saw-tooth distribution and the distribution of average energy with mass had a bell-shaped dis tribution centered about the equal-mass split. The slope of the neutro n multiplicity with kinetic energy had a saw-tooth distribution with a minimum at m approximate to 130. The total excitation energy implied by the measurements was consistent with energy conservation and had a concave distribution with heavy-fragment mass. with a flat minimum be tween m approximate to 132 and 152, suggesting that fragment pairs ar e preferentially formed in a compact configuration at the scission poi nt. (C) 1998 Published by Elsevier Science B.V.