The use of extended libraries of one-group cross-sections in precision nuclide composition calculations confirms the importance of including high-threshold reactions in the libraries. Particular attention is paid to impurity nuclides, which are increasingly relevant in solving problems of nuclear engineering. The existing ambiguity in the formation of extended libraries with high-threshold reactions leads to markedly different concentrations of individual nuclides, including impurities. The effect of extended libraries on the calculated nuclide composition is presented for steel irradiated with a neutron flux of 2.7 ∙ 1015 s−1 cm−2 for an irradiation time ranging from 10 to 1000 days.

In this paper, we propose a model to describe the distribution of electrons near the track of a fast ion. The dependence of the fast-electron flux on time, layer depth, and radial variable is modeled taking into account the statistical weight of each trajectory. The pulse duration in the electron-flux distribution was found to be fractions of ps while the radial size of the cylindrical region, where the transport of fast electrons occurs, reaches tens of angstroms.

An analysis of the impact of high-energy cosmic radiation protons on the onboard electronics of the spacecraft was performed. It has been shown that protons can cause nuclear reactions with the atomic nuclei of electronics material. Residual nuclei formed as a result of a nuclear reaction have sufficiently high energy to cross the sensitive areas of several bits of electronics, and the high ionizing ability of nuclear fragments makes it possible to generate an excess charge of carriers that exceeds the critical charge for upsets to occur simultaneously in several bits of an electronic device.

The anisotropic properties of a layer of carbon nanotubes upon electron reflection have been studied. Only a small part of the incident electrons is found to reflect from a target with a surface layer of oriented carbon nanotubes. Reflection occurs only from a layer of horizontally oriented nanotubes at an angle of incidence greater than 80° and vertically oriented nanotubes at an angle of incidence less than 10°. The effect is explained by peculiarities of the formation of an electron flux in the surface layers of the target.

Low-concentration nuclides – impurity nuclides – are increasingly in demand in radiochemistry for defining more precisely the neutronic characteristics of the medium. On use in precision calculations, impurity nuclides afford more accurate calculations. This article considers aspects of the calculation of one-group cross sections of the high-threshold reactions ( n , nt ), ( n , 2 α ), ( n , 2 p ), ( n , pα ), ( n , nd ), ( n , np ), ( n , 2 nα ), and others in extended libraries and their influence on the nuclide composition of irradiated compositions in calculations using the MZK precision program. This program affords guaranteed accuracy of calculated nuclides, including impurities. A procedure is proposed for calculating one-group cross sections as applied to the spectrum in fast reactors.

— The defect-distribution density reaches its maximum at a depth that depends on the ion energy and mass. This depth decreases with increasing angle of incidence because of the multiple scattering of primary ions in the surface layers of the target. As the ion mass increases, the maximum defect density increases according to a power law. The asymmetry of the maximum in the depth distribution of defects is associated with an increase in the elastic energy loss during ion stopping and with a decrease in the ion-transmission coefficient with increasing layer depth.

The Monte Carlo method is compared with deterministic methods based on solving the transport equation and the molecular dynamics method. The capabilities of commonly used general-purpose programs (SRIM, PENELOPE, MCNP, FLUKA, and GEANT4) for Monte Carlo simulation of the processes of particle passage through matter are analyzed. Possible ways to develop the Monte Carlo method are discussed.

An analytic approximation is proposed for a determination of the distribution of the inelastic energy loss of charged fragments originating from nuclear reactions induced by collisions of protons, photons, and electrons with silicon nuclei. It is shown that, in the energy range between 3 and 10 GeV, the effect of the hadronization process on this distribution for heavy secondary ions increases with incident-radiation energy. A strong asymmetry of the distribution calculated for collisions with relativistic electrons is indicative of a momentum transfer to only a small fragment of the nucleus involved.

We give a brief analysis of the probability of spacecraft on-board electronics (OBE) failures under influence of primary space radiation and products of nuclear reactions, which have a significantly higher ionizing capability. Modern advanced programs based on current nuclear reaction databases can help to provide the description of the nuclear residuals' distributions over charge, mass and kinetic energy, which can be used to estimate the probability and rate of the Single Event Effects (SEE). The obtained results can be used to estimate the upset volume and predict whether a single bit or multiple bits will be upset in a device with certain radiation hardness. A possible contribution of extreme fluctuations in ionizing power of the incident particles in the OBE materials is also discussed.

A method for calculating the cross-section for single event effect (SEE) in the electronics operation is proposed; it is caused by secondary ions — products of the interaction between a high-energy proton with the atomic nucleus of one of the materials of an integrated circuit. To estimate the excess charge generated in this case, the contribution of all secondary ions, including those born outside the sensitive layer, is taken into account in the model. Along with the traditional approach based on inelastic energy losses, the model considers the process of atom ionization in the approximation of the effective ion charge. The new method gives lower values of the number of electron–hole pairs and the SEE cross-section.

The number and the sequence of layers of a tungsten and carbon target changes the energy losses of fast electrons in it. The results of calculations using the GEANT4 and PENELOPE programs agree with each other and show that when passing through a W/C target, electrons lose less energy than in a C/W target. The effect is explained by the redistribution of the deposited energy, which is caused by the reflection of electrons from the interface of materials. An increase in the number of layers leads to a decrease in the influence of the target structure on the distribution of the energy absorbed in it.

Quantum-mechanical models and the Monte Carlo method are used to study the composition and energies of products of nuclear reactions induced by collisions of fast protons with silicon and iron nuclei. It is shown that, at proton energies in excess of 500 MeV, intranuclear cascades at the stage of compound-nucleus formation in a preequilibrium state lead to an increase in the number of secondary ions and to a decrease in their average energy. The respective calculations were performed by means of the TALYS, EMPIRE, GEANT4, and FLUKA code packages.

A theoretical approach is proposed for describing the effect of the number and sequence of surface layers of different compositions on the distribution of radiation defects over the depth of the screened material. It is shown that the energy losses of fast protons penetrating through the tungsten-carbon media depend not only on the thickness and chemical composition of the media but also on the sequence and the number of the layers. Results of calculations using GEANT4 and SRIM programs agree well with each other and show that proton loses a larger amount of energy during the passage through the bilayer W/C target than through the C/W one. An increase in the number of layers leads to a decrease in the influence of the target structure on the distribution of the absorbed energy. This effect is explained by the difference in the stopping powers of neighboring layers.

A method based on experimental data, theoretical models, and the empirical estimation of experimental parameters in the equilibrium charge distribution of ions is proposed to evaluate charge changing cross sections. This method makes it possible to obtain cross sections for loss and capture of one or several electrons in gaseous and solid targets with the inclusion of the influence of excited states of ions and target atoms.

A method based on experimental data, theoretical models, and the empirical evaluation of experimental parameters in the equilibrium charge distribution of ions is proposed to evaluate charge-changing cross sections. This method makes it possible to obtain cross sections (recommended for estimations) for the loss and capture of one or several electrons in gas and solid targets with inclusion of the influence of excited states of ions and target atoms.

A model based on depositing charge in the sensitive volume of an integrated circuit is used to estimate the probability of single event upset as a result of the interaction of single proton with the circuit materials. Calculations of the number of electron-hole pairs produced by the primary proton and secondary ions as a result of inelastic collision with the nucleus in the sensitive volume and surround materials make it possible to estimate the ratio of the contributions of these sources to the deposited charge.