Certain irregularities have been observed in the formation of probability matrices when applying our method for calculating the coincident summing effects occurringin the gamma spectroscopy of radionuclides. They have to do with the fact that, at certain energy levels, transition intensities are not balanced. As this affects the accuracy of our calculation, we have examined the source of those irregularities. This paper presents comments on the evaluation of the 152Eu decay data. The paper offers an analysis of the errors and mistakes that the evaluators have made, in order to facilitate the future work in gamma spectroscopy.

We present an improved statistical method for the calculation of mean lifetime of nuclei in a decay chain with an uncertain relation between mother and daughter nuclei. The method is based on the formation of time distribution of intervals between mother and daughter nuclei, without trying to set the exact mother-daughter nuclei relationship. If there is a coincidence of mother and daughter nuclei decays, the sum of these distributions has flat term on which an exponential term is superimposed. Parameters of this exponential function allow lifetime of daughter nucleus to be extracted. The method is tested on Monte Carlo simulation data.

The life time distribution measurements of the alpha emitter 216Po have been performed with semiconductor detectors. We applied a new method to obtain the distribution of time intervals between the correlated signals of decay of the 216Po. The deduced half-life of 216Po was found to be 144.0(6) ms, supporting the earlier published measurements and with an uncertainty much lower than any other previously reported value.

In this paper we present the results of applying the new approach for calculating coincidence summing effects. The application of analytical approaches to coincidence summing effects makes it possible to predict all summation peaks that occur in the spectrum. Accordingly, based on the value of the peak area in the spectrum and knowledge of probability transitions between excited states of a nucleus, it is possible to determine the efficiency of detection and activity of radioactive sources. This method is successfully applied to the decay of the radionuclide europium Eu-152. It provides a detailed description of the method of forming the matrix corresponding to the final result - determined activities and the efficiency of detection.The importance of the new method is that it allows us to determine the efficiency of detection and activity of radioactive sources directly without calibration of the detector, which is very important in metrology of radionuclides. (C) 2016 Elsevier B.V. All rights reserved.

First test of the 4pi detector for study of exponential law of radioactive decay and possibility of observation of Zeno effect [1-3], measuring the mean life of 216Po is presented. This detector consists of two surface-barrier n-Si(Au) detectors placed in the close contact ( <1mm) to each other. Th foil is used as a generator of Rn- gas. The foil was covered by nuclear filter with 0.4 mm pores and placed in the bottom of vacuum chamber. So, direct alpha-particles can not reach the detector active surface. The measured half-live of 216Po of 143.5 (0.6) ms is in agreement with literature sources. It is shown, that for the definite source the random background correlation counts are mostly caused by the 220Rn - 216Po alpha activities and that it is not an easy task to decrease a background level of units of percents in the time region >4T1/2. Both, the data acquisition system and the vacuum chamber design are presented in brief.

We present a derivation of the Lagrangian for a system of relativistic particles, starting from d'Alembert's principle. We follow the virtually forgotten derivation of Pars, using generally accepted notation, while introducing some new steps in the derivation and clarifying others.

We analyze the widely spread statement that moving clocks go more slowly than those at rest. For purposes of clarifying this statement, we explicitly introduce the periods of clocks, which are absent in the Lorentz transformations. Due to this, the statement under consideration, based exclusively on the direct application of Lorentz transformations, is at least misleading, because it draws conclusions about some physical quantities from equations in which these quantities are not even mentioned. We show explicitly for the first time that in the presence of several different inertial reference frames, three at least, not all the corresponding, physically equivalent, clocks can have the same period. However, there are no physical possibilities whatsoever, which would allow one to find which of them is slower than the others, in any absolute sense. (C) 2014 Physics Essays Publication.

In this work the strong influence of geological factors on the variability of indoor radon is found in two of three geologically very different regions of South-Eastern Europe. A method to estimate the annual mean concentration when one seasonal measurement is missing is proposed. Large differences of radon concentrations in different rooms of the same house and significant difference in radon concentrations in one season comparing it to the others are noted in certain cases. Geological factors that can lead to such behavior are discussed.

In the treatment of 133Ba decay by the method of coincidence summing, the transitions to the first two excited states of 133Cs were ignored in former works. By applying the most accurate values for these transitions available in literature, we include them into the count rate equations and obtain solutions for the corresponding system. As a result of this more accurate forming of count rate equations, some terms, which contain previously ignored transition probabilities, turn out to be more significant than the conventionally included terms. We show that their inclusion in the system of count rate equations leads to fine improvements in the determinations of detection efficiencies and the activity of the 133Ba source.

A new method for deriving counting rate equations describing coincidence summing of gamma and X-rays for germanium spectrometers is developed. It is applied to the decay of 139Ce and 57Co. It is shown that the results obtained using the proposed method are in complete agreement with the results obtained using other methods, however these results are achieved in a much clearer and simpler way.

The subject is a direct measurement of the activities of 133Ba sources by application of the theoretical count rate expressions recently developed by Novković et al.The total uncertainties of the activity of the measured sources, obtained in two manners, are described in this paper. The presented method is successfully tested using a germanium spectrometer with efficiencies of 50%. The accuracy of this method is proved to be comparable with the present methods of the activity measurement of 133Ba.

A new method for theoretical calculation of coincidence summing of X- and gamma rays for germanium spectrometers has been presented. The counting rate equations, derived by this method, enable to determinate peak efficiencies as well as the activity of the source. The root of the counting rate equations can be determined by commercial mathematical programs. The method was applied to the decay of 139Ce and the derived relationships were compared with the Korun's and Martinčić's results obtained by matrix formalism. The method was also applied to the decay of 57Co and the calculated results were confirmed by the experiment.

A method for determining the specific alpha activity of thick sources using a large area ZnS(Ag) scintillation detector is presented. In this method a quadratic relationship between the detector response and window thickness is assumed. This method provides a quick estimation of alpha activity in the sample, so it is an indicative method. The aim of this experimental work is to approve theoretical assumption and to develop a standard routine method for absolute alpha measurements of thick contaminated environmental sources. For this purpose reference material U3O8 and spiked standards of soil were used. Measurements of contaminated soil samples from south Serbia showed the practical application of this method.

A study of the coincidence summing of X- and gamma-rays of 133Ba has been presented. The detailed computation of the 133Ba spectra was performed by application of the previously published theory by Novkovic et al. The theory is based on tracking all decay paths and their outcomes, i.e., deposited energies in the detector and probabilities for those events. The method enables to treat all possible single and sum peaks of 133Ba. The calculations gave the 1788 decay path outcomes, resulting in 167 peak count rates equations and also total count rate equation. More than 50 peaks were recorded by an HPGe spectrometer with 50% relative efficiency. The experimental values of the peak count rates were in good agreement with the theoretical evaluation.

A long time scale experimental testing of the exponential decay law of gold, 198Au, is presented. The experiment has been processed by using a contemporary digital spectrum analyzer. Within the limits of the experimental errors no deviation from the exponential decay law of 198Au has been observed.

The content of impurities in gold foils intended for neutron flux measurements has been determined. The gold foils were irradiated by a high neutron flux and the activities of the activated impurities were measured after a cooling period of 48 days by a HPGe spectrometer. The activated impurities were Zn and Ag, and their content was determined from the measured activities ratio of the isotopes 65Zn and 110mAg to 198Au. The activated isotopes have longer half-lives than 198Au and they could be measured after the cooling period.