5604 K
73 pp.
 
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TitleFission Spectrum
Author(s)Bloch, F.; Staub, H.
Publication DateAugust 18, 1943
Report NumberAECD-3158; LADC-934
Unique IdentifierACC0087
Other NumbersOSTI ID: 4408656; NSA-05-004245
Research OrgLos Alamos Scientific Lab
Sponsoring OrgUS Atomic Energy Commission
SubjectPhysics
KeywordsBeryllium; Cyclotrons; Deuteron Beams; Efficiency; Energy; Fast Neutrons; Fission; Fission Products; Instruments; Ionization; Irradiation; Measured Values; Neutrons; Nuclear Reactions; Protons; Recoils; Scattering; Slowdown; Spectra; Testing; Thermal Neutrons; Uranium 235; Variations
Related Web PagesFelix Bloch, Neutron Induction, and Bloch Equations
AbstractMeasurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951
5604 K
73 pp.
 
View Document 
  


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