On similarity of various reactor spectra and U prompt fission neutron spectrum.

A well-defined neutron spectrum is an essential tool not only for calibration and testing of neutron detectors used in dosimetry and spectroscopy but also for validation and verification of evaluated cross sections. A new evaluation of thermal-neutron induced U PFNS was performed by the International Atomic Energy Agency (IAEA) in the CIELO (Collaborative International Evaluated Library Organisation Project) project; new measurements of Spectral Averaged Cross sections averaged in the evaluated spectrum are to be obtained. In general, a neutron spectrum in the core is not identical to the pure fission one because fission neutrons undergo many scattering reactions, but it can be shown that PFNS and reactor spectra become undistinguishable from a certain energy boundary.

Disentangling the O cross section using light water and heavy water benchmark assemblies.

Fast neutron leakage spectra from the light and heavy water sphere of 30cm in diameter with neutron source in its centre were measured by a stilbene scintillation detector in the region of 1-10MeV in the distance of 85cm from the spheres surface. We use the light and heavy water to eliminate the effect of hydrogen. Cf with the approximate emission rate of 5.

Validation of differential cross sections by means of Cf spectral averaged cross sections.

The results of systematic evaluations of the spectrum-averaged cross section measurements performed in the spontaneous fission Cf neutron field are presented. The Following threshold reactions were investigated: Na(n,2n)Na, Fe(n,p)Mn, Fe(n,α) Cr, Al(n,p)Mg, Al(n,α)Na, F(n,2n)F, Zr(n,2n)Zr and Y(n,2n)Y. The spectrum-averaged cross sections for Na(n,2n)Na, Fe(n,α)Cr and Y(n,2n)Y reactions were measured for the first time.

Natural iron isotopes influence on the neutron transport.

As an iron is the main structural component of nuclear power plants as well as future fusion power plants, the validation of neutron incident data libraries of iron is a must. Presented paper fits into ongoing validation activities and presents measuring neutron leakage spectra in the 0.1-1.

On Fe neutron cross section importance in iron.

The presented paper aims to evaluate the importance of Fe XS in iron by means of measuring the reaction rates of the selected reactions on Fe and measuring a fast neutron leakage spectra from the iron sphere of 100cm in diameter by a stilbene scintillation detector with subsequent XS sensitivity analysis. The reactions involved in the study were Fe(n,p) and Fe(n,α). Measured neutron induced reaction rates in Fe are compared with calculated ones in different nuclear data libraries.

Measurement of reaction rates for different neutron induced reactions in Al.

The presented paper aims to compare various measured neutron induced reaction rates in Aluminium with computed ones in different nuclear data libraries. A Cf neutron source with emission rate of 9.53E8 n/s was used.

High-frequency homogenization for travelling waves in periodic media.

We consider high-frequency homogenization in periodic media for travelling waves of several different equations: the wave equation for scalar-valued waves such as acoustics; the wave equation for vector-valued waves such as electromagnetism and elasticity; and a system that encompasses the Schrödinger equation. This homogenization applies when the wavelength is of the order of the size of the medium periodicity cell. The travelling wave is assumed to be the sum of two waves: a modulated Bloch carrier wave having crystal wavevector [Formula: see text] and frequency plus a modulated Bloch carrier wave having crystal wavevector [Formula: see text] and frequency .