Single-electron detachment cross sections for negative ions of transition elements colliding with gases

Experimental results for the single-electron detachment cross sections for negative ions of transition elements, such as Ti⁻, Cr⁻, Fe⁻, Ni⁻, Cu⁻ and Ag⁻, in collision with noble gases and N₂, are obtained in the energy region of 7-30 keV. The experiments are carried out using the growth rate method.     

Accurate universal parameterization of absorption cross sections II--neutron absorption cross sections

A recent parameterization (here after referred as paper I, Ref. [4]) of absorption cross sections for any system of charged ions collisions including proton -nucleus collisions, is extended for neutron-nucleus collisions valid from approximately 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pair (charged and/or uncharged). The parameters are associated with the physics of the problem. At lower energies, the optical potential at the surface is important and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.     

A simple method of determining the photoeffect cross sections of elements for gamma rays

A simple relation between the total photoeffect cross section of an element and the total attenuation cross section of its compound has been derived. Total attenuation cross sections of some 15 simple compounds have been measured by performing transmission experiments in a good geometry set up. Using these values and with the aid of the present relation, total photoeffect cross sections of elements of Z 47 at 514.0, 661.6, 1115.5, 1173.2 and 1332.5 keV gamma ray energies have been determined and compared with Scofield's theoretical cross sections.     

Theoretical study on fusion dynamics and evaporation residue cross sections for superheavy elements

The nuclear dynamical deformation, the fusion probability and the evaporation residue （ER） cross sections for the synthesis of superheavy nuclei are studied with the di-nuclear system model and the related dynamical potential energy surface. The intrinsic energy and the maximum dynamical deformations for 48Ca＋248Cm are calculated. The effect of dynamical deformation on the potential energy surface and fusion is investigated. It is found that the dynamical deformation influences the potential energy surface and fusion probability significantly. The dependence of the fusion probability on the angular momentum is investigated. The ER cross sections for some superheavy nuclei in 48Ca induced reactions are calculated and it is found that the theoretical results are in good agreement with the experimental results.     

Errors in evaluated neutron cross sections

The underestimation of the errors in the recommended neutron cross sections calculated on the basis of an analysis of measurement results using strict statistical methods is discussed. The basic reasons for the underestimation of the errors in the cross sections are described. A statistical model is proposed — a constant bias model — for taking into account effectively the component of the measurement error that is unknown to the experimentor. The results of a statistical analysis of the measurements of the ratio of the fission cross sections of ²³⁸U and ²³⁵U on the basis of the constant bias model are presented. It is noted that the experimental errors are much higher (on the average by a factor of 2) than the declared errors. The consequences of using the generally accepted method for correcting the errors in the evaluated cross sections are examined for an exactly solvable model example. It is shown that such a procedure does reconstruct the real errors in the evaluated cross sections.__________Translated from Atomnaya Énergiya, Vol. 98, No. 1, pp. 3–12, January, 2005.     

Atlas of photoneutron cross sections obtained with monoenergetic photons

Photoneutron cross-section data obtained with monoenergetic photons are presented in a uniform format. This compilation is current as of January, 1975.     

Theoretical electron-atom elastic scattering cross sections: Selected elements, 1 keV to 256 keV

Calculated differential elastic electron scattering cross sections for 24 selected elements are presented in tabular form in the energy range 1 to 256 keV at values of 2ⁿ keV. The total elastic and momentum-transfer cross sections are tabulated also. Parameters for 12-parameter analytic fits to the differential values are given for 80 elements in a second table. The calculations were done in the relativistic static approximation with relativistic atomic wavefunctions for the heavier elements (Z > 35).     

Reconstruction method of homogenized cross sections

The reconstruction method of homogenized cross sections in the direct response matrix method has been developed. In this reconstruction method, homogenized cross sections, which take into consideration the influences of neighboring fuel assemblies, can be reconstructed with the response relationship of incoming neutron partial currents and neutron production rates. Calculations for heterogeneous multi fuel assembly systems were done to verify the developed method. The thermal energy group fuel assembly cell-averaged homogenized cross sections reconstructed by this method agreed with those evaluated by the direct calculation of the whole system using the Monte Carlo method within 0.2%. The effect using the reconstructed fuel assembly cell-averaged homogenized cross sections in a conventional core analysis code using cross sections homogenized in a fuel assembly cell was also investigated. The results obtained showed that the analysis accuracy of k-infinity can be improved by using the cross sections reconstructed by the method. Because almost no influences on the analysis accuracy could be found related to the divided numbers of the surfaces and the angles, and the response relationship with neutron production rates of fuel rods or a fuel assembly cell-averaged neutron production rate, this reconstruction method is applicable to a conventional core analysis code using homogenized cross sections in a fuel assembly cell.     

Fission cross sections of americium isotopes

Translated from Atomnaya Énergiya, Vol. 64, No. 6, 422–425, June, 1988.