Digital pulse processor for ion beam microprobe imaging

Capabilities of spectroscopic ion beam analysis (IBA) techniques that are available in ion microprobe facilities can be greatly improved by the use of digital pulse processing. We report here development of a digital multi parameter data acquisition system suitable for IBA imaging applications. Input signals from charge sensitive preamplifier are conditioned by using a simple circuit and digitized with fast ADCs. The digitally converted signals are processed in real time using FPGA. Implementation of several components of the system is presented.     

Empirical approach to the description of spectral performance degradation of silicon photodiodes used as particle detectors

The spectral deterioration of Hamamatsu S5821 silicon photodiodes for ion types and energies frequently used in Ion Beam Analysis was investigated. Focused proton beams with energies 430 keV and 2 MeV were applied to generate radiation damage via an area selective ion implantation in unbiased diodes at room temperature. The variations of spectroscopic features were measured “in situ” by Ion Beam Induced Current (IBIC) method as a function of fluence, within the 10⁹–5 × 10¹² ion/cm² range and diode bias voltages, between 0 and 100 V.An empirical model has been developed to describe the radiation damage. Equations are derived for the variations of the normalized peak position and peak width. The derived empirical equations are physically correct, as far as they account for the superposition of the influence of charge carrier trapping by native and radiation-induced defects and for the effect of charge carrier velocity saturation with electric field strength, as well.     

The effect of kinetic and hydrodynamic factors on current efficiency in the chlorate cell process

An equation has been derived which relates the current efficiency of chlorate production to the operational parameters of the process and the constants connected with the events in the diffusion layer of the anode. The latter have been estimated using available literature data and the equation has been tested for the temperature dependence of current efficiency by comparison with experimental results. A fair degree of agreement has been achieved.Partly presented at the XXth CITCE Meeting, Strasbourg 1969.     

Industrial ecology in university curriculum: new M.Sc. Programme in Environmental Management and Cleaner Production

To ensure long-term capacity building in the area of industrial ecology, a new M.Sc. Programme in Environmental Management and Cleaner Production has been developed in the framework of the BALTECH consortium, which consists of technical universities in the Baltic Sea region. The programme was started at Kaunas University of Technology in September 2002. This paper presents prerequisites for the establishment of the new M.Sc. programme , its aims, goals and structure as well as the relation of different subjects of the programme to the concept of industrial ecology.     

Charge collection efficiency mapping of interdigitated 4H–SiC detectors

The Ion Beam Induced Charge (IBIC) technique was used to map the charge collection efficiency (CCE) of a 4H–SiC photodetector with coplanar interdigitated Schottky barrier electrodes and a common ohmic contact on the back side.IBIC maps were obtained using focused proton beams with energies of 0.9 and 1.5 MeV, at different bias voltages and different sensitive electrode configurations (charge collection at the top Schottky or at the back Ohmic contact).These different experimental conditions have been modeled using a two-dimensional finite element code to solve the adjoint carrier continuity equations and the results obtained have been compared with experimental results. The excellent agreement between the simulated and experimental CCE maps allows an exhaustive interpretation of the charge collection mechanisms occurring in pixellated or strip detectors.     

Experimental liquidus study of the binary PbO-ZnO and ternary PbO-ZnO-SiO2 systems

Phase equilibria of the binary PbO-ZnO and ternary PbO-ZnO-SiO₂ systems have been experimentally investigated at 1033–1898?K (760–1625?°C) for oxide liquid in equilibrium with air and solid oxide phases: tridymite or cristobalite (SiO₂), willemite (Zn₂SiO₄), zincite (ZnO), larsenite (PbZnSiO₄) and lead-zinc melilite (Pb₂ZnSi₂O₇) covering the ranges of concentrations not studied before. High-temperature equilibration on primary phase or inert metal (platinum) substrates, followed by quenching and direct measurement of the Pb, Zn and Si concentrations in the phases with the electron probe X-ray microanalysis (EPMA) has been used. Liquidus phase equilibrium data is essential for the development of the thermodynamic model.     

Lead solubility in FeO x -CaO-SiO2 slags at iron saturation

Experiments have been carried out to determine the equilibria between FeO _x -CaO-SiO₂ slag and lead metal in iron crucibles at temperatures ranging from 1473 to 1573 K. It has been found that the highest lead solubilities are observed in the silica-saturated iron silicate slags, while the lowest solubilities are observed in the CaO-saturated calcium ferrite slags. The activity coefficient of PbO varies from 0.15 to 3, depending on the slag composition. Changes in temperature do not have a significant impact on the activity coefficient. The activity of FeO and pct Fe³⁺/pct Fe²⁺ ratios have been determined as a function of slag composition. These new experimental data have been incorporated into an optimized thermodynamic slag model using the computer package FACT.     

Adsorption–desorption noise in plasmonic chemical/biological sensors for multiple analyte environment

We investigated intrinsic noise in plasmonic sensors caused by adsorption and desorption of gaseous analytes on the sensor surface. We analyzed a general situation when there is a larger number of different analyte species. We applied our model to calculate various analyte mixtures, including some environmental pollutants, toxic and dangerous substances. The spectral density of mean square refractive index fluctuations follows a dependence similar to that of generation-recombination noise in photodetectors, flat at lower frequencies and sharply decreasing at higher. Some of the calculated noise levels are well within the detection range of conventional surface plasmon resonance sensors. An AD noise peak is observed in temperature dependence of mean square refractive index fluctuations, thus sensor operating temperature may be optimized to obtain larger signal to noise ratio. A significant property of AD noise is its rise with the decreasing plasmon sensor area, which means that it will be even more pronounced in modern nanoplasmonic devices. Our consideration is valid both for conventional surface plasmon resonance devices and for general nanoplasmonic devices.     

Coupled experimental and thermodynamic study of the Zn-Fe-Si-O system

Experimental and thermodynamic modeling studies have been carried out on the Zn-Fe-Si-O system. This research is part of a wider program to characterize zinc/lead industrial slags and sinters in the PbO-ZnO-SiO₂-CaO-FeO-Fe₂O₃ system. Experimental investigations involve high-temperature equilibration and quenching techniques followed by electron probe X-ray microanalysis (EPMA). Liquidus temperatures and solid solubilities of the crystalline phases were measured in the temperature range from 1200 °C to 1450 °C (1473 to 1723 K) in the zinc ferrite, zincite, willemite, and tridymite primary-phase fields in the Zn-Fe-Si-O system in air. These equilibrium data for the Zn-Fe-Si-O system in air, combined with previously reported data for this system, were used to obtain an optimized self-consistent set of parameters of thermodynamic models for all phases.     

Color‐separating backlight for improved LCD efficiency

Abstract— A large part of the light generated in a backlight is usually absorbed in the color filters of the liquid‐crystal display. A new backlight system that uses a grating to split the white light into different colors and a lens array to focus this light onto the pixels is presented. The absorbing filters can be eliminated and efficiency is improved. The system is characterized, as well as its different components.