Analytical differential cross section of electron elastically scattered by solid targets in the energy range up to 100 keV

In this paper, we propose a new approach to determine the adjustable parameters of differential elastic cross-section of Bentabet et al. approximation. The resultant approximation is an analytical expression that can be used to study the interaction of electron beams with solid targets. This approximation is applied for the energy range up to 100 keV, to calculate some quantities such as: the mean penetration depths, the mean number of wide angle collisions and the backscattering coefficient (BSC) of Al, Cu, Ag and Au semi-infinite solid targets. BSC was calculated by using both the Monte Carlo method and the Vicanek and Urbassek analytical model. The obtained results are compared with the experiment and good agreement is remarked.     

Charging kinetics in virgin and 1 MeV-electron irradiated yttria-stabilized zirconia in the 300–1000 K range

A study performed with a dedicated scanning electron microscope (SEM) on the surface electrical properties of (1 0 0)-oriented yttria-stabilized zirconia (YSZ) single crystals irradiated with 1 MeV electrons is presented. When compared with virgin YSZ, the 1 MeV-irradiated YSZ shows a decrease of the intrinsic total electron emission coefficient σ₀ and an increase of the time constant τ associated with the charging kinetics of the material at room temperature. These measurements performed with the SEM beam at 10 keV indicate that the defects induced by the 1 MeV-electron irradiation generate a positive electric field of the order of 0.5 × 10⁶ V/m at a depth of about 1 μm that prevents electrons to escape. When the SEM beam with a 1.1 keV energy is used, a smaller field (0.5 × 10³ V/m) is detected closer to the surface (20 nm). The fading of these fields during the thermal annealing in the 400–1000 K temperature range provides information on the nature of defects induced by the 1 MeV-electron irradiation.     

Molecular dynamics simulation of ion ranges in the 1–100 keV energy range

Binary collision approximation methods have been conventionally used to describe the slowing down of recoiling ions. In order to better understand the slowing-down process, molecular dynamics methods are more and more used in the literature. However, the computer capacity limits the usefulness of the methods in most practical cases where ion implantation in the 1–100 keV energy range is used. We present an efficient molecular dynamics method for calculating ion ranges and deposited energies in the recoil energy region 100 eV to 100 keV. By taking into account only the interactions that are involved in the slowing-down process, range and deposited energy distributions at higher energies can be simulated. The method is demonstrated by range calculations of 40 keV H atoms in Si, 40 keV He atoms in Ta and 100 eV to 10 keV Si atoms in Si.     

Studies of the knee of the cosmic rays primary spectrum through measurements in the 10–10 eV energy range

In this contribution I review the most recent results obtained by experiments studying the primary cosmic rays spectrum at energies around the knee, i.e. the change of slope observed at .The main results are: the change of slope has been observed in the spectra of all secondary components of extensive air showers. The primary chemical composition gets heavier above the knee. Almost all experiments, with the exception of TIBET ASγ, attribute the change of slope to the light component of cosmic rays. The arrival directions of cosmic rays are highly isotropic.These results favor an astrophysical explanation of the knee either as the maximum energy achievable in galactic sources or of end of the containment inside galactic magnetic fields. Nevertheless the scenario is neither complete nor univocally accepted and relevant informations can be obtained studying the 10¹⁶–10¹⁸ eV energy range.     

Efficiency calibration of a HPGe detector in the [46.54–2000] keV energy range for the measurement of environmental samples

Here we describe a general method of calibrating the efficiency of a Ge γ-ray spectrometer. The method, which is based on the work of Quintana and Fernández (Appl. Radiat. Isot. 47 (1996) 911), can now be applied to many different experimental set-ups including both liquid and solid environmental samples. The method requires two different types of experimental inputs. Firstly, it requires measurements with radioactive sources emitting cascades of γ rays covering the energy range of interest. Secondly, it requires measurements with sources emitting isolated γ rays in order to provide coincidence-summing corrections. On this basis, we establish a general function to describe the energy dependence of the efficiency for the particular geometry and source matrix. The method has been applied to 11 different experimental arrangements to provide efficiency calibrations over the range 46.54–2000 keV with associated uncertainties ranging from 0.1% to 1.8%. This allows high precision measurements with environmental samples, which often have very low activities.     

Optimizing the design of a moderator-based neutron detector for a flat response curve in the 2–14 MeV energy range

The efficiency of a neutron detector with boron trifluoride proportional tubes embedded in a polyethylene moderator was simulated with a Monte Carlo program. A moderator structure where the detector had uniform sensitivity for neutrons from 2 to 14 MeV was determined by simulation. A counter was built based on the simulation results. The counter's efficiencies were calibrated with an Am–Be source and an accelerator that served as a D–D and D–T neutron source. Experimental neutron efficiencies of these sources are approximately uniform. The simulated model was validated by the consistent results between the calculated and experimental data.     

Evaluation of the GSO:Ce scintillator in the X-ray energy range from 40 to 140 kV for possible applications in medical X-ray imaging

The purpose of the present study was to evaluate, under X-ray medical imaging conditions, the X-ray luminescence efficiency (XLE) and the optical quantum gain (OQG) of the Gd₂SiO₅:Ce scintillator in single crystal form, suitable for tomographic applications. Intrinsic physical properties and light emission characteristics of the Gd₂SiO₅:Ce scintillator, were also studied. Both experimental and Monte Carlo techniques were used. Various X-ray tube voltages (40–140 kV), currently employed in X-ray imaging applications, were used. XLE was found to vary slowly with X-ray tube voltage from (0.021±0.003) to (0.017±0.003). OQG varied from (317±18) to (466±23) light photons per incident X-ray. These values were adequately high for imaging applications using the particular energy range. Additionally, it was found by Monte Carlo simulations that for crystal thicknesses higher than 0.5 cm both XLE and OQG reached saturation levels, indicating that higher thickness crystals are of no practical use in X-ray medical imaging.     

Development of a momentum determined electron beam in the 1–45 GeV range

A beam line for electrons with energies in the range of 1–45 GeV, low contamination of hadrons and muons and high intensity up to 10⁶ per accelerator spill at 27 GeV was setup at U70 accelerator in Protvino, Russia. A beam tagging system based on drift chambers with 160 μm resolution was able to measure relative electron beam momentum precisely. The resolution σ_p/p was 0.13% at 45 GeV where multiple scattering is negligible. This test beam setup provided a possibility to study properties of lead tungstate crystals (PbWO₄) for the BTeV experiment at Fermilab.     

A calibration kit of fluorescent standards for the UV spectral range of 230–410 nm

A calibration kit of universal fluorescent standards for the spectral range of 230–410 nm, developed on the base of inorganic solutions of Ce(III) and Pr(III) salts with anions having no intensive absorption bands in the standard operational area was investigated. The kit is intended to calibrate the spectral responsibility of spectrometers, spectroradiometers and spectrofluorimeters in the UV spectral range, and to carry out luminescence quantum yield and decay kinetics measurements.     

Neutron response function for a detector with He counters for the 0.39–1.54 MeV neutron energy range

An experimental study was carried out on the neutron response functions of two neutron detector arrays consisting of 39 ³He proportional counters with a polyethylene moderator for monoenergetic neutrons within the 0.39–1.54 MeV neutron energy range. Experimental data on the sensitivity of neutron counting to a change in neutron energy and the influence of the thickness of polyethylene moderator were obtained. The experimental efficiency curves were compared with the calculated response functions generated by a neutron transport code.     

Generation of neutron multigroup constants in the energy range –10 MeV for light and heavy water at four different temperatures

On the basis of the cross section models of neutron scattering in liquid H₂O and D₂O, which have been developed in the previous papers, we have generated eight sets of multigroup constants (energy-averaged cross sections) for each liquid at 5, 27, 52 and . The multigroup constants cover a wide energy range –10 MeV with 140 energy groups at equal logarithmic intervals and represent an angular scattering distribution by the Legendre polynomial expansion up to order 3. Major characteristics of neutron scattering inherent to liquid water are fully included in terms of coherent and incoherent properties and temperature-dependent quasi-elastic and inelastic scattering. These characteristics are assured by comparison with relevant experimental results of scattering cross section and also by neutron slowing-down and thermalization analysis in liquid H₂O and D₂O. It is shown that the present multigroup constants serve for analysis of neutron moderation from fission/spallation to ultra-cold energies, in combination with the already-generated ones for liquid ⁴He, H₂, D₂ and CH₄ and solid CH₄.     

Dependence of optical properties on the composition in Er-doped xNaPO3–(80 − x)TeO2–10ZnO–10Na2O glasses

Transparent and uniform tellurite–phosphate glasses were prepared and the reason why the substitution of NaPO₃ for P₂O₅ can eliminate the coloration of tellurite–phosphate was discussed. The result of TDA indicated that introducing NaPO₃ into tellurite glasses can improve thermal stability of glass hosts. The compositional dependence of absorption cross-sections of ⁴I_13/2, ⁴I_11/2 and ²H_11/2 level, emission cross-section of ⁴I_13/2 level, host phonon energy, up-conversion and 1.5 μm optical emission intensity as well as and quantum yield for ⁴I_13/2 level in PTEr glasses were investigated too. By analyzing obtained data, authors believe that tellurite–phosphate glasses can be used as potential host material for developing optical amplifiers.     

Embrittlement of a superduplex stainless steel in the range of 550–700 °C

Duplex stainless steels are very attractive materials, combining high mechanical properties with improved corrosion resistance. However, these steels present technical limitations because they can experience embrittlement as a consequence of thermal cycles. Moreover, the higher level of alloying elements (Cr and Mo) in the new duplex generation, called superduplex, accelerates the precipitation kinetics of harmful intermetallic phases, which are the responsible of embrittlement. This fact raises the question of the influence of these cycles on the actual performance of duplex components and structures and on its possible failure during service.

In order to investigate this question, heat treatments in the range of 550–700 °C, with different exposure times and cooling rates, have been made on a superduplex stainless steel type EN 1.4507. The evolution of mechanical properties has been followed by means of hardness measurements, impact and fracture toughness tests, whereas microstructural changes have been identified by using optical and transmission electron microscopy analysis. A correlation between the degree of embrittlement and the different types of precipitates has been established.     

Stability of the tetrahedral motif for small gold clusters in the size range 16–24 atoms

A 20-atom tetrahedral cluster of gold atoms is known to be anomalously stable, relative to more disordered structures. Here, we systematically investigate the nature of this stability and the extent to which it also applies to clusters derived from the tetrahedron by adding or removing Au atoms.     

The standard base of Russia for measuring small direct-current in the 10<Superscript>−16</Superscript>–10<Superscript>−9</Superscript> a range

The present state of the standard base of Russia for measuring small direct-current in the 10⁻¹⁶–10⁻⁹ A range is considered, and the metrological characteristics of the state primary and transferable standards are given. __________ Translated from Izmeritel’naya Tekhnika, No. 11, pp. 40–42, November, 2007.     

Scalable Green Synthesis and Full‐Scale Test of the Metal–Organic Framework CAU‐10‐H for Use in Adsorption‐Driven Chillers

The demand for cooling devices has increased during the last years and this trend will continue. Adsorption‐driven chillers (ADCs) using water as the working fluid and low temperature waste energy for regeneration are an environmentally friendly alternative to currently employed cooling devices and can concurrently help to dramatically decrease energy consumption. Due to the ideal water sorption behavior and proven lifetime stability of [Al(OH)(m‐BDC)] ? x H₂O (m‐BDC^2? = 1,3‐benzenedicarboxylate), also denoted CAU‐10‐H, a green very robust synthesis process under reflux, with high yields up to 95% is developed and scaled up to kg‐scale. Shaping of the adsorbent is demonstrated, which is important for an application. Thus monoliths and coatings of CAU‐10‐H are produced using a water‐based binder. The composites are thoroughly characterized toward their mechanical stability and water sorption behavior. Finally a full‐scale heat exchanger is coated and tested under ADC working conditions. Fast adsorption dynamic leads to a high power output and a good power density. A low regeneration temperature of only 70 °C is demonstrated, allowing the use of low temperature sources like waste heat and solar thermal collectors.     

Optical-constant calculation of non-uniform thickness thin films of the Ge10As15Se75 chalcogenide glassy alloy in the sub-band-gap region (0.1–1.8 eV)

Optical-transmission spectra are very sensitive to inhomogeneities in thin films. In particular, a non-uniform thickness produces a clear shrinking in the transmission spectrum at normal incidence. If this deformation is not taken into account, it may lead to serious errors in the calculated values of the refractive index and film thickness. In this paper, a method first applied by Swanepoel for enabling the transformation of an optical-transmission spectrum of a thin film of wedge-shaped thickness into the spectrum of a uniform film, whose thickness is equal to the average thickness of the non-uniform layer, has been employed. This leads subsequently to the accurate derivation of the refractive index in the subgap region (0.1–1.8 eV), the average thickness, as well as a parameter indicating the degree of film-thickness uniformity. This optical procedure is applied to the particular case of freshly-prepared films of the Ge₁₀As₁₅Se₇₅ ternary chalcogenide glassy alloy. The dispersion of the refractive index is discussed in terms of the Wemple–DiDomenico single-oscillator model. The optical-absorption edge is described using the ‘non-direct transition' model proposed by Tauc, and the optical energy gap is calculated by Tauc's extrapolation. Finally, the photo-induced and thermally induced changes in the optical properties of the a-Ge₁₀As₁₅Se₇₅ layers are also studied.