Cross sections for neutrons of 1970 eV and contributions to fundamental neutron interactions

Abstract

Neutrons of energies within a 50 eV interval at 1970 eV have been selected from reactor neutrons by means of resonance scattering on a target of63Cu and subsequently by the 1970 eV resonance of a80Se target. Insertion of stationary filters and the technique of difference measurements with a resonance filter resulted in a high selectivity, which allowed the determination of cross sections for quasi-monoenergetic neutrons for the elements: H, C, O, F, Na, Mg, Al, Si, P, Cl, K, Ca, Sc, Ti, V, Mn, Co, Ni, Cu, Ga, Pb and Bi. The precision cross sections of Pb and H contribute to investigations of fundamental neutron interactions. The measured σ(Pb)=11.198±0.003 b was recently used to deriveα n=(0.8±1)10−3 fm3 for the electric polarizability of the neutron. The neutron-proton cross sectionσ(1 H)=20.13±0.03 b and data at 143 keV, 〈1.3〉 MeV, 〈2.1〉 MeV and from the literature provide a refined set of the scattering parameters for the shape-independent effective-range approximation of the neutron-proton interaction.