No abstract available

[en] Investigations of copper neutron-activation detectors which permitted to improve measurement accuracy of induced activity have been carried on. ⁶³Cu(n, γ)⁶⁴Cu activation reaction rate for copper detectors was compared with ¹⁹⁷Au(n, γ)¹⁹⁸Au reaction rate for which nuclear-physical characteristics are the most reliable. Activation detectors in the form of discs of 10 mm diameter and 25 and 100 μm thickness for copper and 3 μm for gold were used in the experiments. Detectors were simultaneously irradiated in thermal neutron fields. A number of measurements with copper detectors protected with 0.9 and 1.5 mm thick aluminium screens were carried out. Screens were placed at 5 and 10 cm distances from a scintillation unit. A value eta is suggested to be equal 0.343 on the basis of experimental results instead of 0.368 value earlier recommended (eta-quantum yield per one act of ⁶⁴Cu nuclide decay). A correction coefficient value taking account of absorption in the screen should be taken equal to 1.02 for 0.9 mm thick aluminium screen. ⁶³Cu(n, γ)⁶⁴Cu reaction cross section turned out to be equal to 4.50+-0.05 bar

No abstract available

[en] The neutron balance equation in the age approximation is proposed as an additional condition imposing restrictions on form of the neutron spectrum for a unique solution of the improper problem of reconstructing a neutron spectrum. The solution is not limited to the range of application of the age approximation and can be extended to a medium containing water. The geometric parameter and a number of other quantities that appear in the expression for the neutron spectrum are determined from the condition for best agreement between the measured and calculated activation integrals

No abstract available

[en] Standardization of neutron-activation means of measuring in intense reactor fields are considered and recommendations for experiment planning are given. Nuclear-physical characterisrics of activation reactions for measuring in intense neutron fields are presented

[en] The technique for the neutron energy spectra measurement at nuclear-power plants (NPP) based on the neutron activation method is considered. Revealed is the advantage of relative measurements for the cases when the spectrum of the investigated field is determined using the another well studied neutron field. The conseption of the reference neutron field as a metrological object is introduced and its classification is proposed. The problems of the reference field qualification are considered. Made is a conclusion that the above conseption of ''reference neutron field'' may be regarded as the standard for measuring (measure) qualification of the NPP neutron fields over the neutron flux differential density (neutron differential spectrum)

[en] A compound detector based on the ²³Na(n,γ) reaction in a boron shield is investigated. The detector cross section was calculated assuming that the spectrum inside the shield is a sum of two components, one due to direct penetration of neutrons through the shield wall and neutrons scattered in the shield mass. Also investigated was the effect of hydrolyzing varnish in the shield and the size of the activation detector on the detector readings

[en] Application of direct α-radiometry of soil samples for assessment of the fallout density of alpha-nuclides on soils in the vicinity of the Chernobyl NPP is considered. Accounting of the background counting of natural alpha-nuclides contained in soil is conducted and final error is evaluated

No abstract available