Results 1 - 10 of 300
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[en] A comparative analysis of radio-and electro-thermoluminescence phenomena in crystallizing polymers and nano composites based on super molecular polyethylene (UHMWPE) and nano-SiO2 is carried out. The effect of low doses of γ-radiation on the electrophysical properties (ε ', ε '', Te) of UHMWPE/ a- SiO2 nano composites was studied. It was found that the dispersion of nanoparticles and crystallization conditions of the composite significantly affect the ETL and RTL features. It is shown that as in the creation of nano composite UHMWPE / α- SiO2 and y-exposure decrease the intensity of y, P -relaxation processes.
[en] The work is devoted to the study of the influence of the laws of defect formation and transformation of energy in the field of action of γ radiation in borosilicate systems. In addition, in order to determine the focal position of the boron atoms in the initial and irradiated samples conducted by research radio thermoluminescence (RTL) and electro-physical methods.
[en] Full text : Variation of boron concentration in the oxides and the change of its coordination allows to operate largely their properties that is interesting from the point of view of use borosilicate as perspective materials in radiation materials science. The process of changing the coordination of boron in the glasses is not only a factor quantitative ratio between boric anhydride and oxides, but also their nature. One way to change the coordination of boron in the borosilicate is a gamma irradiation. In this work we first obtained the radiothermoluminescence curves (RTL) of gamma - irradiated borosilicate (B2O3/SiO2) in the temperature range 80-300 K. Depending on the content of boric anhydride (0.5-10 mass. percent) and the absorbed radiation dose (D gamma = 0, 50kGr 5) have been studied the features of RTL and identified the kinetic laws of change of boron coordination in the irradiated borosilicate. The ultimate concentration of boron substituting silicon in crystal lattice of borosilicate corresponds 1,5 percent content of B2O3 in SiO2. It was established that irradiation of borosilicate relatively low doses of gamma - quanta allows to change the coordination of boron in the SiO2.
[en] Repeated stimulation by infrared of a feldspar sample causes a reduction in the luminescence signal. The initial rate of loss of luminescence due to infrared stimulation is investigated for a microcline and an orthoclase with preheating at 150 deg. C, 180 deg. C and 220 deg. C for times ranging from 20 to 2400 s
[en] This paper is a general guide to recommended annealing procedures for some of the commonly used radiothermoluminescent materials. Annealing procedures differing from those given in the guide may be more appropriate for some preparations of the materials. (author)
[en] This paper reviews the physics of the phenomenon of thermoluminescence (TL) related to dosimetric applications. Basic concepts are given using the one trap-one recombination centre model. In spite of its simplicity the kinetics of this model appears very useful in the understanding all fundamental features of the luminescence production and provides a framework to interpret many observations. The efficiency in the distinct steps in the luminescence production (production electron-hole pairs, trapping, transfer, recombination and emission) are described and discussed in view of the efficiency of known TL materials
[en] Kinetic parameters are evaluated for the thermoluminescence (TL) of geological samples of the feldspar albite (NaAlSi3O8). Both natural and laboratory-induced TL curves are studied between RT and 5000C. The natural TL shows an intense peak at about 3400C while the lab-induced glow curve consists of a peak near 2000C, with a long high temperature tail. The kinetic analysis of the two glow curves shows that both can be described in terms of the same series of discrete traps, with the activation energies: 0.64, 0.71, 0.93, 1.08, 1.25, 1.64 and 1.85 eV. The intensities of the low temperature peaks in the natural TL were found to be rather high in view of the half-lives of the relevant traps. This might be due to tunnelling of charge carriers from deeper traps. This should be taken into consideration when samples of albite are used for geological and archaeological dating or in accident dosimetry. (author)
[en] An investigation was carried out into the distribution of optical absorption, radioluminescence and thermostimulated luminescence (TSL) in large corundum crystals with defects. The dependence of energetic and stochastic parameters of the TSL process on stimulation temperature was analysed for detectors cut from fixed crystal points. TSL, proceeding by the mechanism of structural thermally initiated rearrangements and pure centre structures, was shown to provide the occurrence of a unique set of operating parameters for ionising radiation thermoluminescent detectors made of this material. (author)
[en] Molecular relaxation in a series of polyethylene samples has been investigated by radiothermoluminescence. Polyethylene structure is discussed in terms of different modes of molecular mobility in different structural regions. Each of the low temperature transitions is assigned to a certain structure region and structural unit(s). The influence of different polyethylene molecular parameters and processing conditions on its structure and mechanical properties is also considered