Elementary Cross Sections Research Articles

Measurements and analysis of the radar cross section of chaff dipoles

AbstractA free space test method to measure the Radar Cross Section (RCS) of single dipole elements is presented. The method is such that dipoles can be measured over a large range of frequencies, in free space and without the need of an anechoic chamber. The setup employs with a Vector Network Analyser (VNA) synchronised to a rotating turntable that controls the position of the transmitting and receiving antennas and the polarisation of the irradiated electric field. Measurements are collected for chaff dipoles made of copper wire, microwire and aluminised glass, from 5 to 11 GHz, to allow a comparison of chaff RCS properties with respect to chaff material and method of fabrication. Measurements of the copper wire chaff also allowed a comparison with existing theoretical predictions of chaff reflectivity. An analysis and a comparison of the results is presented. Results show that the experimental trends of the chaff RCS curves agree with the theoretical RCS curves for perfectly conducting wires. They also show that copper wire provides the strongest reflective chaff followed by the aluminised glass and the microwire.

Empirical calculation of K-shell fluorescence cross sections for elements in the atomic range 16≤Z≤92 by photon effects ranging from 5.46 to 123.6 keV (Three-dimensional formulae)

Abstract The main objective of this study is to obtain three-dimensional empirical K-shell X-ray fluorescence cross-section (σKα,σKβ and σKtot) values for a wide range of elements 16≤Z≤92 for photons with energies from 5.46 keV to 123.6 keV, using more than 3300 experimental data values published between 1985 and 2023 by numerous researchers. These data values are fitted using an interpolation method including a three-dimensional function against atomic number Z and excitation energy E, resulting in a three-dimensional plot to estimate empirically a three-dimensional set of Kα, Kβ and Ktot X-ray fluorescence cross sections. The results of this empirical calculation are compared, for selected elements, with other empirical and experimental values reported in the literature, and a reasonable agreement is observed.

Assessing the impact of nuclear mass models on the prediction of synthesis cross sections for superheavy elements

Assessing the impact of nuclear mass models on the prediction of synthesis cross sections for superheavy elements

A study on the resist performance of inorganic-organic resist materials for EUV and electron-beam lithography

In the realization of further miniaturization at scales of 10 nm and below in semiconductor devices, it is essential to create new resist designs, such as hybrid inorganic-organic resist materials for ionizing radiation, in order to clarify the effect the structure of metal resist on resist performance. In this study, some hybrid inorganic-organic resist materials known as metal-oxo clusters were synthesized, and their lithographic characteristics were investigated to clarify the relationship between resist performance, such as sensitivity, resolution, and their absorption coefficient or cross section, and the density of their elements by using EUV and electron-beam (EB) exposure. Our results indicated that the sensitivity in Hf-based oxo clusters was higher than that of Ti-based and Zr-based oxo clusters in both EB and EUV exposure. Although the exposure dose was not optimized, the patterns of Ti-based, Zr-based, and Hf-based oxo clusters showed 100, 50, and 32 nm line-and-space patterns at doses of 250, 80, and 25 μC cm−2, respectively. We clarified that it is very important for new resist designs such as hybrid inorganic-organic resists to increase the photo-absorption cross section and density of elements for EUV and EB without degradation of film quality. In addition, the size and homogeneity of the building blocks and film quality are very important for the resist performance of hybrid inorganic-organic resist materials. Furthermore, it is clarified that the etch durability of metal-oxo clusters is higher than conventional resist materials, and this is much increased by annealing them at 800 °C.

Stress equalizing in optimal design of High-Toughness lattice structures

In this paper, the recently proposed structural optimization strategy, the Galilei-Optimization (GO), is adapted for improving the toughness response of a holed two-dimensional lattice system made of a network of micro-beams whose geometrical arrangement was prescribed. By taking advantage of the possibility of minimizing stress gradients and stress peaks around the hole via GO, we redesigned the cross sections of the lattice beam elements, equalizing the stresses over the entire domain. Consequently, the resulting optimized microstructure highlighted a significant enhancement of the overall toughness due to a drastic decrease of the stress concentration factor in the hole proximity, preserving the initial stiffness and lowering the total overall weight. To validate the robustness of the procedure and the numerical Finite Element outcomes, two non-optimized and optimized structures were actually built up through 3D printing and tested in the laboratory under the same boundary conditions used for the simulations. This evidence confirmed the effectiveness of the proposed method in obtaining optimized beam-like plates with high toughness, which could pave the way for designing new light materials with extreme mechanical performance well beyond the sole stiffness and strength.

Assessment of mitigation alternatives for differential shortening in high-rise reinforced concrete buildings

Selecting appropriate structural system for reinforced concrete (RC) buildings is essential in the design process to satisfy serviceability and strength requirements. Using ordinary analysis (OA) may result in inaccurate estimation of differential shortenings (DS) between vertical supporting elements which might lead to structural and architectural problems. Efficiency of staged analysis including time-dependent effects (SAT) has been recently recognized for the analysis of these buildings due to considering the sequential nature of construction. In this research, eight RC buildings with heights ranging between 35 and 175 m and various structural systems, namely rigid frames (RF), shear walls (SW), wall frames (WF), and tube in tube (TT), are analyzed. An assessment is conducted for the adequacy of three mitigation alternatives to decrease changes between DS estimated using OA and SAT. In Alternative 1, cross sections of all vertical elements (columns and shear walls) are increased by 50%. Alternative 2 is performed by iteratively proportioning the dimensions of internal columns without changing the cross sections of edge and corner vertical elements. One outrigger system is introduced along the height of buildings with WF and TT systems in Alternative 3. Analysis of the eight buildings is implemented by developing a numerical model considering the construction stages and time-dependent effects. The alternatives assessment is conducted by comparing differential displacements (DD), bending moments, and shearing forces before and after mitigation obtained from OA and SAT. The numerical results showed that Alternative 1 is not efficient in mitigating the differences between the OA and SAT for all the studied buildings. However, an optimum solution can be achieved using the Alternative 2 for all investigated systems. Also, Alternative 3 was found adequate in partially mitigating the differences between the two analyses for the buildings with WF and TT systems.

Features of calculations of normal cross sections of reinforced concrete structures according to SP 63.13330.2018

Introduction. SP 63.13330.2018 provides two approaches to calculating the strength of normal cross-sections of reinforced concrete structures: the nonlinear deformation model NDM (general approach) and the method of ultimate forces UFM for simple elements of rectangular, T-shaped and I-shaped sections with reinforcement located at the edges of the element. As far as the authors are aware, no detailed studies have been conducted to compare the results obtained with both approaches.Aim. Conduct researchе to compare the results obtained in the calculations for NDM and UFM, identify the differences, establish their physical cause, evaluate the economic aspects of the problem, and make the necessary recommendations.Materials and methods. Calculations were carried out according to the program "OM SNiP Reinforced Concrete". Studies were performed for three types of structures. The first type included four cross sections of elements under two stress states: bending (T-shaped and rectangular), off-center compression (rectangular and annular). The second type of structures included beams tested at the NIIZHB named after A.A. Gvozdev. The third type is lintels according to State Standard 948-84. In all types of structures, under the action of the same forces, reinforcement was selected according to NDM and UFM.Results. It turned out that the compressed zone of concrete in UFM participates in the resistance of cross sections to acting forces much more effectively than in NDM. This can lead to a significant difference in reinforcement. In one of the cases, the steel consumption in the calculations for UFM turned out to be 78 % less than for NDM. Conclusions. For the considered structures, the calculation of the strength of normal cross sections by UFM turned out to be more effective than by NDM. At the same time, all the necessary regulatory requirements are met. Further research is needed to amend the existing regulations.

Measurement of flux distribution of an AmBe neutron source and estimation of two group integral capture cross-sections

Neutron capture cross sections of elements are of utmost importance in reactor physics, dosimetry applications and stellar nucleosynthesis studies. Manipal Centre for Natural Sciences (MCNS) possesses a 16Ci AmBe neutron source, which is housed inside a concrete structure. The neutrons undergo multiple scattering events in the concrete structure and surrounding materials; therefore, the neutron flux profile is unique to this source and structural material, which differs from the standard ISO spectrum. Using this AmBe source, experiments are being conducted to understand the neutron energy distribution in two groups to measure capture cross sections of various isotopes. In the present work, gold has been used as a flux monitor, and the indium cross-section has been measured in two groups. These foils (Gold and Indium) are irradiated with and without cadmium cover to understand the neutron spectra in two spectral regions as cadmium cutoffs neutrons of energy below 0.5 eV. Irradiated samples were counted in High-Pure Germanium (HPGe) detector, and the γ-spectra obtained were used to get the epi‑cadmium (0.5 eV and above) to total ratio of ⟨σ(E)ϕ(E)⟩. The neutron flux is estimated in two groups corresponding to thermal (thermal energy neutron extended up to 0.5 eV) and epi‑cadmium regions, and also the flux-weighted capture cross sections of 115In are determined.

Probing the high-density symmetry energy from subthreshold hyperon production in heavy-ion collisions

The hyperon dynamics in heavy-ion collisions near threshold energy has been investigated within the quantum molecular dynamics transport model. The isospin and momentum dependent hyperon-nucleon potential and the threshold energy correction on the hyperon elementary cross section are included in the model. It is found that the high-density symmetry energy is dependent on the isospin ratios Σ−/Σ+ and Ξ−/Ξ0, in particular in the domain of high kinetic energies. The isospin diffusion in heavy-ion collisions influences the neutron/proton ratio in the high-density region. The Σ−/Σ+ ratio depends on the stiffness of symmetry energy, in particular at the beam energy below the threshold value (Eth=1.58 GeV), i.e., the kinetic energy spectra of the single ratios, excitation functions and energy spectra of the double ratios in the isotopic reactions of 108Sn + 112Sn, 112Sn + 112Sn, 124Sn + 124Sn and 132Sn + 124Sn. The double strangeness ratio Ξ−/Ξ0 weakly depends on the symmetry energy because of the hyperon-hyperon collision mainly contributing the Ξ production below the threshold energy (Eth = 3.72 GeV).

Experimental low velocity proton and 28Siq+ induced X-ray production cross sections for select elements within 24 ≤ Z ≤ 83

Particle Induced X-ray Emission (PIXE) spectroscopy is an effectively well-established analytical technique in the low projectile mass (Z < 3) regime. This is in part due to the availability of fairly accurate theoretical models of fundamental interaction parameters such as the X-ray production cross section (XPCS). Continual development of widely used theoretical models such as the ECPSSR theory with adapted corrections in the United Atom limit (UA), Electron Capture (EC) and Multiple Ionisation (MI); requires a rich database of experimental X-ray production cross sections. Beyond the scope of proton PIXE, validated reliable theoretical models may be useful for the accurate approximation of heavy ion induced X-ray production cross sections for Heavy Ion PIXE. This requires persistent efforts aimed at contributing to the currently sparse heavy ion induced X-ray production cross section database. In this work, we report on a new experimental dataset of low energy XPCS in the 0.3 MeV/u – 1.0 MeV/u ion velocity range in Cr, Ni, Ge, Mo, Sn, W, Au and Bi due to proton and 28Siq + ion impact, with an aim at enriching and updating the current database.

A Parametric BIM Framework to Conceptual Structural Design for Assessing the Embodied Environmental Impact

Decisions made in the early design stage have a significant effect on a building’s performance and environmental impact. In practice, a conceptual design is performed by an architect, while a structural engineer begins to work in later phases when the architectural concept has already evolved. However, the geometry and form of a building directly determine the type of structure and applicable materials; therefore, the conceptual design phase gives rise to examining alternative solutions. This paper presents a method for generating alternative structural solutions in the conceptual design phase and examining their embodied environmental impact by integrating parametric design and building information modeling (BIM). Rhinoceros and Grasshopper were used to develop the parametric script, which includes the generation of geometrical variations, the automatic definition of initial cross sections for the load-bearing elements based on in-built structural design approximations, the datasets for embodied environmental impact of the used building materials, the generation of life cycle inventory (LCI), the automatic calculation of life cycle assessment (LCA) results based on the geometry, and the conversion of the parametric model into building information model. The method was demonstrated using a case study of 48 different alternative solutions for an unheated warehouse made of steel frames. Based on the results, the areas with the greatest energy impact were identified. The case study analysis also illustrated that the applied cross section may have a significant effect on the impact categories. The results draw attention to the complexity of LCA calculations even in the case of a simple structure containing a limited number of variables, where parametric design can serve as an effective tool for a comprehensive environmental impact assessment.

A Distribution Feature Prediction Method for Chaff Using Polarized Scattering Data

This letter proposes a method to obtain the distribution features of a chaff cloud by using its polarized scattering data, which provides a new way to filter the jamming of a chaff cloud. First, the electromagnetic polarization algorithm is adopted to acquire the radar cross section (RCS) of a single element with the incident wave revolving on its axis. The direct-accumulating summation method is then employed to obtain the RCS of a chaff cloud. Whereafter, using integer least squares, we can extract the distribution features, i.e., the lengths, orientations, and mixing ratio of chaff elements. Finally, several measurement and simulation cases are carried out based on the actual scenarios. The errors of extracted distribution features are less than 0.06, which indicates that this method can accurately extract the distribution features of a chaff cloud.

New measurement of the elemental fragmentation cross sections of 218 MeV/nucleon Si28 on a carbon target

Elemental fragmentation cross sections (EFCSs) of stable and unstable nuclides have been investigated with various projectile-target combinations at a wide range of incident energies. These data are critical to constrain and develop the theoretical reaction models and to study the propagation of galactic cosmic rays (GCR). In this work, we present a new EFCS measurement for $^{28}$Si on carbon at 218~MeV/nucleon performed at the Heavy Ion Research Facility (HIRFL-CSR) complex in Lanzhou. The impact of the target thickness has been well corrected to derive an accurate EFCS. Our present results with charge changes $\Delta Z$ = 1-6 are compared to the previous measurements and to the predictions from the models modified EPAX2, EPAX3, FRACS, ABRABLA07, NUCFRG2, and IQMD coupled with GEMINI (IQMD+GEMINI). All the models fail to describe the odd-even staggering strength in the elemental distribution, with the exception of the IQMD+GEMINI model, which can reproduce the EFCSs with an accuracy of better than 3.5\% for $\Delta Z\leq5$. The IQMD+GEMINI analysis shows that the odd-even staggering in EFCSs occurs in the sequential statistical decay stage rather than in the initial dynamical collision stage. This offers a reasonable approach to understand the underlying mechanism of fragmentation reactions.

Boosting Photo Upconversion in Electropolymerised Thin Film with Yb/Er Complexes

AbstractUpconversion luminescence (UCL) in organometallic complexes has attracted great interest in photovoltaics and biological applications due to their fascinating energy transfer mechanism from low‐energy photon to high‐energy photon. However, photon‐upconversion operating in a single discrete entity remains a challenge caused by low‐absorption cross section of the luminescent lanthanide element. Here, a novel upconversion system is reported combining Yb (Ytterbium) sensitizers and Er (Erbium) activators in the film by electropolymerization, which leads to excited‐state absorption (ESA) and energy transfer upconversion (ETU) processes. For the first time, the UCL has been achieved in the thin films upon near‐infrared laser irradiation, and the upconversion intensity exhibits up to 30‐fold enhancement with the variation of Yb/Er ratio.

Improved methods for calculating electron, positron, and photon radiation-induced displacement damage cross sections

Radiation damage is a key challenge for materials. Accurate evaluation of radiation damage is a starting point for investigating the behaviors of materials used in a radiation environment. The present work proposes improved methods for calculating the primary radiation damage cross sections induced by light particles, including electrons, positrons, and photons. The main improvements compared with previous methods are: (1) accurate Mott cross section rather than the McKinley-Feshbach analytical approach is used for electron and positron scattering; (2) data and methods recommended by the International Commission on Radiation Unit and measurements (ICRU) are systematically applied for computing the stopping powers of electron and positron; (3) accurate differential cross section by combining different models instead of some simple approaches is used for pair production. The electron, positron, and photon irradiation-induced displacement cross sections for various important elements covering a large range of atomic numbers (from Li to U) are computed with the improved methods for energy up to 100 MeV. The calculated displacement cross sections are also tabulated so that they can be simply used for further applications.

Trihedral lattice supports geometry optimization according to the stability criterion

The study proposes a technique for optimizing trihedral lattice tower structures from the condition of maximum critical load. Towers with a cross section of elements in the form of round pipes are considered. The load is represented by a horizontal concentrated force at the upper end of the tower, simulating the operation of a wind turbine. A constraint on the constancy of the mass of the structure is introduced. The variable parameters are the width of the tower, which varies in height, the height of the panels, the external diameters of the cross-section of the chords and lattice. The solution of the nonlinear optimization problem is performed in the MATLAB environment using the Optimization Toolbox and Global Optimization Toolbox packages. A tower of constant width is taken as the initial approximation. The calculation of the critical load is performed by the finite element method in a linear formulation by solving the eigenvalue problem. To solve the nonlinear optimization problem, the interior point method, the pattern search method and the genetic algorithm are used. The efficiency of the listed methods is compared. It has been found that the interior point method is the most efficient. The critical load for the optimal tower compared to the tower of constant width with the same mass increased by 2.3 times.

Elemental fragmentation cross sections for a 16O beam of 400 MeV/u kinetic energy interacting with a graphite target using the FOOT ΔE-TOF detectors

The study of nuclear fragmentation plays a central role in many important applications: from the study of Particle Therapy (PT) up to radiation protection for space (RPS) missions and the design of shielding for nuclear reactors. The FragmentatiOn Of Target (FOOT) collaboration aims to study the nuclear reactions that describe the interactions with matter of different light ions (like H1, He4, C12, O16) of interest for such applications, performing double differential fragmentation cross section measurements in the energy range of interest for PT and RPS. In this manuscript, we present the analysis of the data collected in the interactions of an oxygen ion beam of 400 MeV/u with a graphite target using a partial FOOT setup, at the GSI Helmholtz Center for Heavy Ion Research facility in Darmstadt. During the data taking the magnets, the silicon trackers and the calorimeter foreseen in the final FOOT setup were not yet available, and hence precise measurements of the fragments kinetic energy, momentum and mass were not possible. However, using the FOOT scintillator detectors for the time of flight (TOF) and energy loss (ΔE) measurements together with a drift chamber, used as beam monitor, it was possible to measure the elemental fragmentation cross sections. The reduced detector set-up and the limited available statistics allowed anyway to obtain relevant results, providing statistically significant measurements of cross sections eagerly needed for PT and RPS applications. Whenever possible the obtained results have been compared with existing measurements helping in discriminating between conflicting results in the literature and demonstrating at the same time the proper functioning of the FOOT ΔE-TOF system. Finally, the obtained fragmentation cross sections are compared to the Monte Carlo predictions obtained with the FLUKA software.

Adapting Overlap Per Two Floors for Vertical Structural Members:Column and Shear Wall

The main aim of this study is adapting overlap per two floors for vertical structural members for column and shear wall. Since this concept is new and not applied widely in Ethiopia, the challenges, technical solution for challenges and economic differences were assessed and drawn. This study was used qualitative and quantitative research methodologies. The amounts of reinforcement bars were determined. In depth interviews, site observation, theoretical concepts, previous practical experience and secondary data were used. Purposive sampling technique was applied for selection of respondents and their working companies. In depth interviews were interpreted with respect to structural, architectural and cost perspectives. The results obtained from the purposively selected interviews, observations, theoretical concepts, practical experience and referring secondary materials for providing overlap per two floors on all columns and shear walls has no any effect on the architectural aspects of the column and shear wall. Because, overlapping per two floors for columns and shear wall does not affect the shape and cross section of the vertical elements and covered completely by concrete. Typically, the analysis of cost of reinforcement bars was done for G + 10 building. The total percentage of wastage of bars per two floors is reduced by 13.51% and 11.11% for 2.7m and 3.5m story height compared to per one floor respectively. Key word s: Overlap, Shear wall, Column, Challenge, Solution, Cost DOI: 10.7176/CER/14-6-01 Publication date: October 31 st 2022

Theoretical attempt to predict the cross sections in the case of new superheavy elements

For the first time, within the framework of the dynamical cluster-decay model (DCM) by Gupta and collaborators, we provide reasonable estimations for cross sections of nuclear systems which will give rise to new superheavy elements. The important point and the new approach presented in this contribution are the theoretical calculations done without tracking any reference to experimental data; i.e., these are independent calculations. We will provide a method for reasonable estimates for the cross sections of unobserved possible decay channels in a nuclear reaction. We will demonstrate the capability of the DCM to give a probable/sensible range of the cross section. This exercise of theoretical calculations within the DCM may benefit experiments for the discovery of new superheavy elements. Our results can provide hints to the experimentalist to choose proper incoming channels in order to perform experiments. We have applied this new strategy to calculate the cross sections of the already studied compound nuclei $Z=116$ and 118 via hot fusion reactions, and observed that our calculated range of cross sections has given values within the reach of experimental studies. Both compound nuclei were studied earlier by one of the authors for the angle $\mathrm{\ensuremath{\Phi}}={0}^{\ensuremath{\circ}}$, including quadrupole deformations, ${\ensuremath{\beta}}_{2i}$ alone with ``optimum'' orientations (${\ensuremath{\theta}}_{\mathrm{opt}.}$). Here, we consider the same specifications in order to study the new approach using the DCM. The principal aim of this work is to study the capability of the DCM to determine the cross sections for new elements, where experimental data are not available.

Analytical Formulas for Approximating Cross Sections of Electron Collisions with Hydrogen, Noble Gases, Alkali and Other Atoms

This paper presents an analysis of data on the cross sections of elastic and inelastic collisions of electrons with noble gases, alkali and other atoms. For the selected sets of experimental and theoretical data, optimal analytical formulas are found, and approximation coefficients are calculated. The obtained semi-empirical formulas reproduce the values of the transport (diffusion), excitation and ionization cross sections for noble gases. Much attention is paid to the ionization cross sections of metal atoms, which are often present as an impurity in gas-discharge plasma. The approximation formulas reproduce the values of the ionization cross sections for hydrogen, metal and other elements in a wide range of energies with accurate orders of errors of the available theoretical and experimental data. For some elements with a two-hump plot of the dependence of the ionization cross section on the collision energy, it is proposed to use a two-term formula that takes into account ionization from both external and internal shells.