[en] Gamma-ray spectra of terra rossa soil and natural-phosphate ore have been measured in order to determine Th, U, K and ¹³⁷Cs contents. It has been found that the phosphate ore contains an order of magnitude lower potassium content than average (n.10^-3g/g) an average content of thorium (n.10^-6g/g) and a two orders of magnitude higher concentration of uranium (n.10^-4g/g) than the average found in the Earth's crust. Terra rossa contains two to three times higher concentrations of Th and U, average concentrations of K, and up to 0.2 Bq/g of ¹³⁷Cs. It is considered that both materials are suitable for large sample calibration purposes and are applicable for radioecological studies of soils. (author)

[en] It has been shown that dominant ²²⁷Ac impurity in some non highly purified lanthanum compounds as La(NO₃)₃x6H₂O or La₂O₃, together with its daughters, can be used for efficiency calibration of Ge-detectors in the energy range from 50 keV to 1500 keV, using ¹³⁸La to determine the ²²⁷Ac activity. These compounds are recommended for the calibration of voluminous liquid and powdery samples. (orig.)

[en] Two coaxial Ge(Li) spectrometers A and B with respective relative efficiencies of 5.4 and 22.3% with FWHM better than 2.5 keV have been used in a detailed study of background spectrum in the energy range from 0.03 to 80 MeV. The lead castle (effective thickness 15 cm) was originally constructed for a smaller spectrometer (A), its integral background count rate for energies above 30 keV amounts: N(>30 keV)=0.88+-0.01 cps, which allows to measure specific activities (concentrations) of 7 Bq/kg. This shielding is not good enough for the larger detector (B,N>2 cps) but due to its high peak to compton ratio (46:1) it allows to determine even lower specific activities (1 Bq/kg). Detector B has been used to detect ¹¹³Cd(n,γ)¹¹⁴Cd and H(n,γ)D reactions induced with ''natural neutrons'' through the observation of 558.7 and 2223.7 keV gamma lines. The line at 558.7 keV will be recommended to settle the criterion for ''line observability'' in the background spectrum of a shielded detector. Both detectors have been used to measure μ-mesonic dEsub(μ)/dx spectrum. (author)

No abstract available

[en] The problem of maintaining a low-level spectrometer free of contamination under conditions of high environmental contamination is of significant concern to monitoring laboratories. A chance to test the procedures for protecting our HP-Ge detector arose during the first stages of the Chernobyl incident. The background gamma-ray spectra of the 8% efficiency shielded low-background HP-Ge detector in the energy range of 60-2,700 keV before and after the Chernobyl accident had been investigated. In the measurement performed just the day before a radioactive cloud reached the area, the total count rate in that energy range was found to be 0.58 c.p.s. The highest rates between 0.8 and 0.9 c.p.s. were obtained 4-7 days after the accident. In the measurement from about 70 days after the accident, the rate was 0.59 c.p.s. (i.e., very close to the rate value before the accident). The presence of some 14-15 fission products have been confirmed in measurements of gamma spectra of samples taken from outside the laboratory, shortly after a radioactive cloud spread all over the country. In the background spectrum taken 70 days later, only gamma lines of three isotopes remained: ¹⁰³Ru(39.2d), ¹³⁴Cs(2.06y), and ¹³⁷Cs(30.14y). 1 ref., 1 fig. 1 tab

No abstract available

[en] We suggest that radioactive food contamination, as determined solely by a quantitative gamma-ray spectroscopic measurement, may, apart from the total activity per unit mass, be for quick reference conveniently characterized by another single figure which we call the ''Gamma Contamination Food Factor'' (GCFF). This factor may be defined as the ratio of the total specific activity of gamma-ray-emitting radionuclides in the food sample (except that of ⁴⁰K) to the specific activity of ⁴⁰K either in the sample itself or in an ''average man''. We discuss briefly the meaning and advantages of these definitions. (author)

[en] The long-lived γ-radionuclidic impurities in the columns of spent ⁹⁹Mo/^99mTc generators one year after the calibration date have been determined by γ-spectrometry. Three radionuclidic impurities fission products (¹⁰³Ru, ¹⁰⁶Ru and ¹²⁵Sb) were detected. Also in the majority of samples, three radioisotopes of tungsten (¹⁸¹W, ¹⁸⁵W and ¹⁸⁸W) were also present. The contents of the impurities were found to vary greatly. According to the activity, energy and half-life, the main contribution to the residual activity in the spent generators is due to the presence of ¹²⁵Sb. (author). 4 refs., 1 tab

[en] Determination of ¹³⁸La activity in La₂O₃ from the known activity of ⁴⁰K in KCl has been described. Activity of ¹³⁸La was determined by the least square fit of the efficiency curve ε=a . E^b through the three points: (788 keV, ε(A)), (1436 keV, ε(A)) and (1461 keV, ε(⁴⁰K)), taking the activity A of ¹³⁸La as a free parameter. The activity of the best fit has been taken as the ¹³⁸La activity. (orig.)

No abstract available