Prompt Neutron Emission Multiplicity Distributions and Average Values, <ν>, at 2200 Meter per Second for the Fissile Nuclides
Brookhaven National Laboratory
Upton, New York 11973, USA
The prompt neutron emission multiplicity distribution, Pν, is of interest for methods of self-calibration and for auto-correlation to assay fissionable material for nuclear safeguards. <ν>, the average value of Pν, is of interest at neutron thermal energies since it is related to the neutron multiplication factor and it is used as a normalizing point for energy dependent values of <ν>. Values of Pν and <ν> have been determined at the standard neutron energy of 0.0253 ev for the neutron induced fission of the four fissile nuclides, 233,235U, and 239,241Pu. Revised <ν> values have been obtained by re-evaluating <ν> experiments measured at 2200 meter/second relative to the <ν> from the spontaneous fission of 252Cf. These revised values of <ν> have been used to renormalize the measured Pν values. The revised values of <ν> are all about 1/4% to 1/2% smaller than the corresponding values of ENDF/B-V.
KEYWORDS: <ν>, Pν, En = 0.025 ev, 233U, 235U, 239Pu, 241Pu