The spontaneous fission neutron spectrum of Cf 252 from 0.2 to 7.0 Mev has been measured. Time-of-flight techniques were employed to determine the lower energy portion of the spectrum while proton recoils in emulsions were used to study the higher energy neutrons. The measured neutron spectrum is, within the experimental accuracy, described by the empirical relation N(E) ocexp[-0.88£(Mev)] sinh[2.0E(Mev)]*, where N(E) is the number of neutrons of energy E per unit energy interval. The experimental results are compared with the theoretically determined Cf 252 fission neutron spectrum.
699 event were of high energy. A subsequent investigation employing apparatus primarily designed to measure electron velocity spectra is contemplated. Such spectra are of interest because according to the Weizel-Beeck theory of ionization by ions, a quasi molecule is formed during an ionizing collision, and it seems likely that the 1 M. Deutsch and J. Rotblat, Atomic Energy Commission Report .
Neutron elastic-scattering cross sections of indium are measured from 4.5 to 10 MeV at intervals of =500 keV. Seventy or more differential values are obtained at each incident energy, distributed between = 18 and 160'. These are combined with lower-energy data previously obtained at this laboratory, and with 11and 14-MeV results from the literature, to form a comprehensive elasticscattering database extending from = 1.5 to 14 MeV. These data are interpreted in terms of a conventional spherical optical model. The resulting potential is extrapolated to the bound-state regime.It is shown that in the middle of the 50-82 neutron shell, the potential derived from the scattering results adequately describes the binding energies of particle states, but does not do well for hole states. The latter shortcoming is attributed to hole states having occupational probabilities sufficiently different from unity so that the exclusion principle becomes a factor, to rearrangement of the neutron core, and to the fact that the shell-model potential was assumed to have an energyindependent geometry. The systematic behavior of the real optical potential is discussed, and it is shown that the isovector strength deduced from neutron scattering is consistent with the nucleonnucleon scattering data when a mass dependence of the radius is used.
Operated by THE UNIVERSIW OF CHICAGO for the U. S. DEPARTMENT OF ENERGY under Contract W-31-109-Eng-38 Argonne National Laboratory, with facilities in the states of Illinois and Idaho, is owned by the United States government, and operated by The University of Chicago under the provisions of a contract with the Department of Energy.
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