Precision Measurements Of The Neutron Proton Total Cross Section At 3204 Mev And 5858 Mev

We have completed a new set of total cross section measurements, snd have measured approximately 36 additional samples. The goal of the new measurements was 1% statistical accuracy in 1% energy bins with systematic errors less than 1%. This was achieved for all but the smallest samples, for which the statistical accuracy was as large as 2% in 1% bins. However, the energy resolution is significantly better than this at low energies. The samples were: * The APT spallation target material: W * Medium-mass stmctural materials: Ti, V, Cr, Mn, Fe, Co, Ni * Actinides: Th, depleted U * Other materials for global optical model development: F, Mg, P, S, K, Y, Mo, In, Au, Hg, natural Pb * Separated isotopes of light nuclei: 6Li%, 7Li, 1°B, 11B, 13C, * Medium- and heavy-mass separated isotopes: {sup 54,56}Fe, {sup 182,183,184,186}W * Few-nucleon physics: H, D.

Neutron total cross sections were measured for 26 elements. Data were obtained in the energy range from 47 keV to 20 MeV for 11 elements in the range of light-mass fission products. Previously reported measurements for eight heavy and actinide isotopes were extended to 20 MeV. Data were also obtained for Cu (47 keV to 1.4 MeV) and for Sc, Zn, Nd, Hf, and Pt (1.8 to 20 MeV). The present work is part of a continuing effort to provide accurate neutron total cross sections for evaluations and for optical-model parameteriztions. The latter are required for the derivation of other nuclear-data information of importance to applied programs. 37 references.