Inelastic Cross Sections from Gamma-ray Measurements


Book Description

Measurements of gamma rays following neutron induced reactions have been studied with the Germanium Array for Neutron-induced Excitations (GEANIE) at the Los Alamos Neutron Science Center (LANSCE) for many years. Gamma-ray excitation functions and coincidence studies provide insight into nuclear reaction mechanisms as well as expanding our knowledge of energy levels and gamma-rays. Samples studied with Ge detectors at LANSCE range from Be to Pu. Fe, Cr and Ti have been considered for use as reference cross sections. An overview of the measurements and efforts to create a reliable neutron-induced gamma-ray reference cross section will be presented.




Cross Section Measurements for Neutron Inelastic Scattering and the [math][mo]([/mo][mi]n[/mi][mo], [/mo][mo] [/mo][mrow][mn]2[/mn][mi]n[/mi][mi][gamma][/mi][/mrow][mo][/mo][/math] Reaction on [math][mrow][mmultiscripts][mi]Pb[/mi][mprescripts/][none/][mrow][mn]206[/mn][/mrow][/mmultiscripts][/mrow][/math].


Book Description

We measured excitation functions for [gamma] production associated with the neutron inelastic scattering and the (n, 2n) reactions on 206Pb from threshold up to 18 MeV for about 40 transitions. Two independent measurements were performed using different samples and acquisition systems to check consistency of the results. Moreover, the neutron flux was determined with a 235U fission chamber and a procedure that were validated against a fluence standard. For incident energy higher than the threshold for the first excited level and up to 3.5 MeV, estimates are provided for the total inelastic and level cross sections by combining the present [gamma] production cross sections with the level and decay data of 206Pb reported in the literature. The uncertainty common to all incident energies is 3.0% allowing overall uncertainties from 3.3% to 30% depending on transition and neutron energy. Finally, the present data agree well with earlier work, but significantly expand the experimental database while comparisons with model calculations using the talys reaction code show good agreement over the full energy range.










Fast Neutron Cross Section Measurements. Final Technical Report, March 1, 1987--September 30, 1995


Book Description

The time-of-flight technique was used with the ring scattering geometry in a laboratory with low neutron scattering background to measure the angular distributions of the cross sections for elastic and inelastic scattering of 14 MeV neutrons in natural chromium, iron, nickel, and niobium. Specifically for inelastic scattering included were: the 1.43 MeV and 4.56 MeV levels of 52Cr, the 0.85 MeV level, and (2.94-3.12) MeV and (4.46-4.51) MeV level groups of 56Fe, the 1.33 MeV level of 6°Ni combined with the 1.45 MeV level of 58Ni, and the 4.48 MeV level of 58Ni. Pulses of neutrons with time width of 0.9-1.1 ns were produced via the 3H(d, n)4He reaction in a 150 keV Cockcroft-Walton linear accelerator, with average intensities of 9x108 n/s. The energy of the incident neutrons was between 14.75 MeV (at 16°) and 13.48 MeV (at 160°). High purity scattering ring samples were used. The scattering angles ranged from (almost equal to)16° to (almost equal to)150°, for iron, chromium, and nickel, and from (almost equal to)16° to (almost equal to)160° for niobium, with a typical step of (almost equal to)10°. High purity ring samples were used.




Neutron Cross Sections


Book Description