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In this paper, we propose a new method for double sided diffusion of lithium ions into a monocrystalline silicon wafer for the further fabrication of Si (Li) p-i-n nuclear radiation detectors with a diameter of the sensitive surface of more than 110 mm and a thickness of the sensitive region of more than 4 mm. It was found that the optimal regime for lithium diffusion into large-diameter silicon is at a temperature of T = (450 ± 20) °C, time t = 3 min, thickness hLi = (300 ± 10) mm. The theoretical assumptions and experimental characteristics of double sided diffusion are considered. As initial material the dislocation free monocrystalline cylindrical silicon crystal of the p-type, obtained by the floating-zone method (with a diameter 110 mm, thickness 8-10 mm, resistivity ρ=1000 ÷ 10000 Ohm·cm and life time τ = 500 μs) and the silicon crystal of the p-type (with a diameter of 110 mm, resistivity ρ = 10 ÷ 12 Ohm·cm, lifetime τ = 50 μs, grown in an argon atmosphere) obtained by the Czochralski method were used. Correspondingly, the technological processes of mechanical and chemical processing of semiconductor wafers based on silicon of a large area have been improved. [ABSTRACT FROM AUTHOR]

Nuclear techniques and other techniques using ionising radiation represent a valuable tool in non-destructive diagnostics applied to archaeological finds and objects of arts, namely for determining the composition of materials used in the production of artefacts. X-ray fluorescence analysis, both in its energy form and in its wave dispersive form, is one of the most widespread methods using ionising radiation to study the elemental composition of materials. It is frequently used for studies of various cultural and historic relicts and objects of art. This work summarizes the authors’ experience with X-ray fluorescence analysis in investigating historical frescos namely by means of portable provide spectroscopic devices. The results of these measurements information on the composition of the pigments, enable the comparison of processes used in the fabrication of pigments by individual artists, and in many cases offer information on how to repair the damaged parts.

Large active volume Si(Li) detectors were successfully developed for γ-ray spectrometry at room temperature that show a sufficient efficiency and an energy resolution that is better than scintillation detectors. The higher efficiency of the proposed detectors with respect to normal silicon diodes is achieved by increasing the active volume. For this purpose special attention is given to the selection of the initial material which has to show homogeneous electro-physical parameters, low concentration of oxygen impurities and high structural perfection. The technique of using lithium ions is used as these drift into large depths and hence the profile of the impurity distribution is optimized. [Copyright &y& Elsevier]

Si(Li) detectors are currently being developed for use in large Compton telescopes. A major advantage of silicon when compared with germanium is its ability to operate at significantly higher temperatures. To determine the feasibility of using Si(Li) detectors in a Compton telescope, their performance as a function of temperature has been studied. We present leakage current, noise data and gamma-ray spectral performance at various temperatures for single 6-mm-thick planar devices. It has been determined that for detectors without a guard ring, the noise began to rise significantly around 210 K. Adding a guard ring improved the leakage current by about an order of magnitude and reduced the total noise (detector plus electronics) by about 25%. The noise of the detectors with ∼130 mm2 area and a guard ring did not exceed our performance goal of 2 keV FWHM until the temperature was approximately 240 K. For 122 keV gamma rays, no evidence of ballistic deficit was seen at 8 μs peaking time and bias voltages corresponding to an internal electric field of ∼1150 V/cm. Some evidence of ballistic deficit was seen for 662 keV gamma rays at temperatures above 220 K. [Copyright &y& Elsevier]

A digital signal processor, based upon high-rate sampling of the preamplifier output, and equipped with rise time and pulse shape discrimination, has been tested in three situations. This processor provided significant improvement of particle induced X-ray emission and X-ray fluorescence detection limits over the state of the art analog processors, depending on the energy and intensity distribution of the X-ray spectra. Additionally it had a superior performance when measurements were performed in an environment of large electronic noise and in large nuclear background environment. It has also improved the reduction of several artifacts in X-ray spectra. [Copyright &y& Elsevier]