Scattering of 14.5-Mev Neutrons by Complex Nuclei

Abstract

New measurements of the differential elastic scattering cross sections of C, Al, Fe, Cu, Sn, Pb, and U for 14.5-Mev neutrons are reported. For Fe, Cu, Sn, and Pb the angular range from 5° to 150° was investigated with ±1° to db3° angular resolution. For the other elements a smaller angular range was investigated. Particular effort was devoted to the problem of discriminating against inelastically scattered neutrons and methods were developed which provided an experimental energy resolution of ^500 kev. Limited differential cross section data for inelastically scattered neutrons of energy greater than 9 Mev are also presented for Fe, Cu, Sn, and Pb.

Measurement of the elastic scattering cross section of neutrons from argon and neon

“…Wick's limit [25,26] sets a lower limit on the differential elastic scattering cross section at zero degrees by relating the zero-degree cross section to the total neutron cross section using the optical theorem. Although this quantity only represents the contribution from the imaginary part of the scattering amplitude, it is known to be nearly an equality [27,28].…”

Neutron Cross Sections of Nitrogen, Oxygen, Aluminum, Silicon, Iron, Deuterium, and Beryllium

“…At 14 MeV we analyzed the composite distribution, given in the second edition of BNL-400, 36 which is made up from the work of Elliot, 87 Yuasa, 88 Coon et al, 27 and Anderson et al 89 We did not, however, use the work of Khaletskii 40 The Legendre coefficients are given in Table 21.…”

“…Between 1.55 and 5 MeV we were guided by the trend of the data, although our curve did not often pass through points resulting from analysis of the measured distributions. From 0.3 to 1.5 MeV we used Chien's data,28 and below 0.3 MeV we used Langsdorf's data 27. For the extrapolation to 18 MeV we followed the trend of the data below 14 MeV consistent with the necessity of avoiding Wick limit violations on the one hand and avoiding generation of negative cross sections on the other.…”

Small-Angle Scattering of 7-14-MeV Neutrons by Pb and U

“…(l-#) 3 , for x so near 1 and Q 2 so large that vW 2 ~ W u then this theory would be wrong. However, at present we are simply unable to test the theory with available data, since changing the scaling variable, and hence the treatment of nonscaling contributions, changes the apparent form of W u and even more vW 2i since x is not sufficiently close to 1 that vW 2~Wim 9 Order K corrections to o L /u T are expected to vanish near threshold as the first power of 1-x; A. Zee, F. Wilczek, and S. B 0 Treiman, Phys. Rev.…”