No abstract available

[en] In recent years multigroup sensitivity profiles and covariance matrices have been added to the Radiation Shielding Information Center's Data Library Collection (DLC). Sensitivity profiles are available in a single package. DLC-45/SENPRO, and covariance matrices are found in two packages, DLC-44/COVERX and DLC-77/COVERV. The contents of these packages are described and their availability is discussed

[en] Illustrative cases of the use of neutron scattering in the study of the electronic properties of materials discussed here include scattering by localised electrons, narrow band materials and electron plasmas. (U.K.)

[en] Several topics of current interest are discussed including energy and intensity standards, direct thermal neutron capture, primary E2 transitions in (n,γ) reactions, nonstatistical effects in resonance neutron capture, transmission measurements of Sc employed in 2-keV facilities, and tests of Axel-Brink predictions of γ-ray strength functions via average resonance capture

[en] Energy distribution of the first and second neutrons from (n,2n) scattering event in ²³⁸U was evaluated according to the consistent compound nucleus model recently proposed by Segev. The law for deriving the energy distribution of secondary neutrons from a (n,2n) scattering event, depends on whether the reaction is considered as a simultaneous emission of two neutrons from one compound nucleus, or a successive emission of neutrons from different compound nuclei. Segev has presented a means of calculating the energy distribution assuming the latter model. The laws presented in the ENDF/B data files suggest the former model. The evaluation was based on inelastic level excitation and evaporation data for ²³⁸U and ²³⁷U. Data was retrieved from ENDF/B files. The evaporation data for ²³⁷U was based on (γ,n) reaction ²³⁸U. The inelastic level excitation data for ²³⁷U was evaluated at the Soreq Nuclear Research Centre. It is concluded from the application of Segev's model to ²³⁸U, that the energetic spectrum of secondary neutrons, is harder in the high range of energy than the one predicted by the use of the distribution law presented in ENDF/B data files. The spectrum of secondary (n,2n) neutrons, resulting from the interaction of 14 MeV neutrons in ²³⁸U calculated with Segev's model, is compared with the corresponding spectrum of the LLL library, ENDF/B library and the recent evaluation of BNWL. It is found that the spectrum evaluated by LLL and BNWL is harder than that evaluated with Segev's model

[en] The search for antineutrons in the neutron beam was made using a scintillation detector at 70 m from the IBR-30 reactor. It is found that the antineutron number does not exceed 1.7x10^-10 from neutron number. That sets for neutron oscillation period in vacuum the lower limit of about 200 s

[en] The neutron capture cross sections of the stable neodymium isotopes have been measured with high energy resolution in the keV region at the 40 m station of ORELA. Average resonance parameters are extracted for s-wave resonances. Significant positive correlations are found between gamma-n-0 and gamma-gamma for all isotopes. The magnitude of the observed correlation coefficient, particularly for ¹⁴²Nd (rho = 0.9), cannot be explained in terms of valence neutron capture and additional mechanisms are discussed. The average s-wave radiative widths for the odd-A isotopes are markedly greater than for the even-A isotopes, while the p-wave radiative width for ¹⁴²Nd is considerably less than the s-wave width. (author)

[en] In this paper we report the results of a comprehensive investigation on the low (ω < or approximately 400 cm^-1) and very low (0.2 cm^-1 < or approximately ω < or approximately 40 cm^-1) frequency vibrational and structural dynamics in water and aqueous solutions of ZnCl₂ (for concentrations up to saturation). Time-of-flight inelastic neutron scattering and Raman spectroscopy were used to obtain the vibrational frequency distributions and the frequency dependence of the Raman electron vibration coupling function. Structural relaxation times were determined by depolarized Rayleigh wing scattering. The results, which confirm that these systems are best viewed as ''locally amorphous solids'', are discussed in terms of locally ordered, dynamically correlated patches in which structure and dynamics are strongly influenced by the solute, especially by its action on the water hydrogen bond

[en] Two-level model to calculate transmission functionals and self-shielding factors for fissile nuclides in the unresolved resonance region is presented. To similate quasi-resonance cross section structure, average resonance parameters, statistical parameter distributions and gaussian low order quadratare formulae are employed. Theoretical predictions and experimental data for ²³⁹Pu are compared

[en] Results of developing a technique of subgroup solution of transition equation in media with a strong resonance cross section structure, are presented. The subgroup approach permits to take into account the spatial dependence of selfscreening of group cross sections which is mainly vivid in heterogeneous cells close to separation boundaries of physical zones in thick layers of resonance disperser. The solution of this problem has practical value for problems of homogenization of cells and preparation of constants for shielding calculation. It also can be used for methodic investigations in the estimate of errors of the group method