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- Author or Editor: I. Chereji x
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Abstract
A useful method for crystal detector calibration by using point sources is presented. The method is applied to determine the total efficiency of a 80×80 mm NaI/Tl/ crystal in an energy window suitable for134Cs+137Cs activity evaluation in a sample of 750 cm3.
Abstract
Research carried out at IIMT Cluj-Napoca in the field of radioisotope abundances had in view the improvement and application of the methods of low-level counting to various problems in geology, hydrology, radioecology, archaeology, etc. During the last 25 years some progress has been made in improving techniques of low-level radioactivity measurements by constructing low background detection systems and by developing new and rapid methods for detector calibration and sample preparation. So, the conventional methods for U, Ra, Th and Rn determination in natural waters were completed with the construction and development of gas-filled proportional counters for tritium and carbon-14 analyses in the environment. According to a national program of radioecological studies, analyses of elemental U, Ra, Th and Rn in waters from the Danube Delta area were begun in 1991. The artificial component of radioactivity was also followed in fallout, rainfall, soil, ground water, food, drugs and pharmaceutical plants especially after the Chernobyl disaster.
Abstract
A comparison between the counting parameters of solid and liquid scintillation methods for radon determination in water is attempted. The counting efficiency is better for a toluene-based liquid scintillator but, as the background is considerably higher than in solid scintillators, the figure of merit and the lower limit of the measurable activity are favorable for a scintillation counter based on zinc sulfide (Ag activated) scintillator.
Abstract
Further improvement of the counting sensitivity of a proportional gas counter is obtained by using ethane synthesized from acetylene and hydrogen, where thesample of tritiated water is used for acetylene production as well as for hydrogen generation. In this way all six hydrogen atoms of the filling gas molecule arise from the active sample. The advantage of this sample preparation procedure is obvious especially in the case of low-level tritium measurements.
Abstract
The evolution of Chernobyl103Ru,134Cs and137Cs in accumulated fallout is rigorously followed. The103Ru activity of about 12 kBq.m–2 in the middle of May 1986 became insignificant at the end of 1986, while the levels of134Cs and137Cs have changed during 3 years from 2.5 kBq.m–2, respectively, 5 kBq.m–2 to about 0.9 kBq.m–2, respectively 4.7 kBq.m–2 according to their proper half-lives.
Abstract
The methods applied for natural uranium, radium and thorium determinations in water samples are shortly presented together with some preliminary results. The measurements will be continued as part of an extended program of ecological study of the Danube Delta area.
Abstract
Results of measurements carried out in 1992 on water samples drawn from the Danube Delta area are presented. All the values obtained, including also the Rn contents determined on the spot, are below the maximum permissible concentrations for drinking water.
Abstract
The cesium rarioactivity (owing to134Cs and137Cs) in a number of wild plants of phamaceutical interest harvested in Transylvania was followed during the 1986–1994 period. The data give information on major pathways of vegetable organism contamination through lives from fallout and resuspention and by root uptake from contaminated soil.
