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In this paper, the procedure for determination of the mean value of non-homogenous background radiation and the expression of measurement uncertainty is considered. The background radiation is described using the Student's distribution, and the measurement uncertainty using the Welch-Satterthwaite equation. The proposed algorithm was experimentally verified under well-controlled laboratory conditions and satisfactory results were obtained. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 171007]

Man is constantly exposed to radiation from the radionuclides from the environment. This study presents the results of measuring the absorbed dose rates of natural ionizing radiation in rural areas in the municipality of Štrpce, in southern part of Kosovo and Metohija. The measurements were conducted in 20 houses in two cycles: when rooms were not heated, and when they were warmed up in the same season. Ten observed houses were with basement rooms, and ten others were without basements. The absorbed dose rate of radiation was measured by Gaiger-Miller's counter DR-M3. Mean value of the measured absorbed dose rate was 1.93 µGy/h - in the first cycle and 1.47 µGy/h - in the second cycle. At the same time the values of the absorbed dose of radiation in the environmental were measured, and obtained values were 1.77 µGy/h and 1.33 µGy/h, respectively. Relations between absorbed dose in the premises and in the environment were 1.09 in first cycle, and 1.1 in the second cycle of measurements.

In this paper we analyze application of contemporary methods of insulation co-ordination and the enlargement law in designing a GM counting tube. It has been shown that by applying insulation co-ordination methods the counting tube can be optimally dimensioned. The application of the enlargement law was demonstrated in generalizing the results of test obtained by the GM tube to those obtained by the counting tube with m-times greater dimensions. The investigations were conducted both theoretically and by experiment. Using theoretical analysis, we derived the expressions that may be applied if a performance function of a random variable breakdown voltage is known. The experiments were conducted on a GM counter model under well controlled laboratory conditions.

In this paper, a portable gamma-ray spectrometer for real-time and in-situ gamma-ray detection applications is presented. By combining a quasi-hemispherical CdZnTe (CZT) semiconductor detector and a Geiger-Muller (GM) counter together, a wide dose rate range is achieved, ranging from 0.1 μSv/h to 100 mSv/h with a relative error of less than 10%. The GM counter is used to measure dose rate from 1 mSv/h to 100 mSv/h. With CZT, the spectrometer can provide a high energy resolution spectrum for nuclide identification and a high precision dose rate at low dose rates. The full width half maximum (FWHM) resolution is 2.2% at 662 keV below 70 μSv/h and is better than 3.3% at 3.8 mSv/h. The weight of the spectrometer is 3.2 kg for handheld and the runtime is up to 12 h without charging. For preliminary applications, the spectrometer was used to measure the gamma radiation around the Back-n white neutron beam line at China Spallation Neutron Source and around the steam generator in the nuclear power plant at Daya Bay Nuclear Power Station. • The design of a portable gamma-ray spectrometer based on CZT and GM counter was proposed. • High energy resolution of 2.2% at 662 keV and wide dose rate range from 0.1 μSv/h to 100 mSv/h. • Radioactive sources were used to calibrate the spectrometer and examine its performance. • Preliminary application for gamma radiation detection around a neutron beam and in nuclear power plant. [ABSTRACT FROM AUTHOR]

This paper investigates, through theory and experiment, the influence of the plain-parallel electrode surface dimensions change on the type A measurement uncertainty of a GM counter. The possibilities of applying these results to practical structures are examined by using the methods of mathematical statistics. Special attention is devoted to the influence of electrode surface enlargement on the statistical behavior of the pulse number random variable, expressed in the form of the enlargement law. In the theoretical part of the paper, the general surface enlargement law is derived. Comparison of experimental results with those predicted by the surface enlargement law proved its validity for expressing the type A measurement uncertainty of GM counters constructed with a plain-parallel electrode configuration with a homogenous electric field.

GM counters are often used in radiation detection since they generate a strong signal which can be easily detected. The working principal of a GM counter is based on the interaction of ionizing radiation with the atoms and molecules of the gas present in the counter's tube. Free electrons created as a result of this interaction become initial electrons, i. e. start an avalanche process which is detected as a pulse of current. This current pulse is independent of the energy imparted on the gas, that being the main difference between a GM counter and the majority of other radiation detectors. In literature, the dependence on the incidence of radiation energy, tube's orientation and characteristics of the reading system are quoted as the main sources of measurement uncertainty of GM counters. The aim of this paper is to determine the dependence of measurement uncertainty of a GM counter on the volume of its counter's tube. The dependence of the pulse current on the size of the counter's tube has, therefore, been considered here, both in radial and parallel geometry. The initiation and expansion of the current pulse have been examined by means of elementary processes of electrical discharge such as the Markov processes, while the changes in the counter's tube volume were put to test by the space - time enlargement law. The random variable known as the 'current pulse in the counter's tube' (i. e. electrical breakdown of the electrode configuration) has also been taken into account and an appropriate theoretical distribution statistically determined. Thus obtained theoretical results were then compared to corresponding experimental results established in controlled laboratory conditions.

The paper discusses statistical methods that can be applied when constructing the Geiger–Muller counters to obtain the same response to radiation, regardless of their dimensions. This issue is relevant for the improvement of the early warning system of potential damage to the barrier of a container with radioactive material that can escape through a damaged barrier and contaminate the natural environment. The method of statistical mathematics was used to design such counters. Two laws of mathematical statistics were used, the law of similarity for electric discharges and the law of increasing probability. The Geiger–Muller​ counter chambers designed in this way have been tested experimentally. The experiments were performed under well-controlled laboratory conditions at a low value of combined measurement uncertainty. The obtained results confirmed the efficiency of the proposed and applied methods. [ABSTRACT FROM AUTHOR]

This paper deals with possible ways of obtaining expanded and combined uncertainty in measurements for four types of GM counters with a same counter’s tube, in cases when the contributors of these uncertainties are cosmic background radiation and induced overvoltage phenomena. Nowadays, as a consequence of electromagnetic radiation, the latter phenomenon is especially marked in urban environments. Based on experimental results obtained, it has been established that the uncertainties of an influenced random variable ′number of pulses from background radiation′ and ′number of pulses induced by overvoltage′ depend on the technological solution of the counter’s reading system and contribute in different ways to the expanded and combined uncertainty in measurements of the applied types of GM counters.

89Sr, a pure beta emitter with half life of 50 .53 d is used as its chloride solution for palliative care of bone metastases. This paper describes the feasibility studies that have been conducted at FBTR, IGCAR for production of this radionuclide using the 89Y( n, p)89Sr reaction. Yttria pellets were irradiated in a special subassembly at the core centre for a total of 73 d in two steps of 35 d and 38 d with a time gap of 38 d. The irradiated yttria target was dissolved in nitric acid and the bulk Y was separated by solvent extraction using the TBP-HNO3 complex. The 89Sr fraction was purified using the cation exchange resin DOWEX 50W×8 (100-200 mesh size) from the other radioactive impurities seen. The eluted 89Sr fraction was assayed using a GM counting system. The 89Sr activity produced in 1 g of yttria pellet was found to be 19 mCi. [ABSTRACT FROM AUTHOR]

The paper presents the results of testing the Geiger-Muller chamber cathode radii on the GM counters characteristics. The influence of the cathode radius is tested on: 1 - the GM counter characteristic; 2 - the length and plateau slope; and 3 - the GM counter chamber lifetime. The influence of small amounts of electronegative gas in the GM chamber working gas on the observed characteristics was also analyzed. The obtained results differ drastically from the results of similar tests presented in previously published papers on similar topics. This result is explained by the fact that the law of similarity for gas emissions was taken into consideration when making the tested tubes (i.e., the mean free path length of the electron was treated as a geometric parameter). In that way, the relevant results for the application of GM counters in practice were obtained. The result obtained with a small percentage of electronegative gas in the three-component mixture of gases noble gas + quenching gas + electronegative gas confirms the positive synergistic effect of the electronegative gas addition. This result contradicts the general view that GM chamber working gas must not contain electronegative gas. • Testing the Geiger-Muller chamber cathode radii on the GM counters characteristics. • Experimental GM chamber designed using the law of similarity for electric discharge in gases. • Chamber with gas mixture (He + Cl + SF6) showed that a small amount of SF6 shortens the dead time. • Chambers of different dimensions provided almost identical results for the same flux of incident particles. • Experimental results were statistically processed using U test. [ABSTRACT FROM AUTHOR]

Abstract: Characteristics of the dead time of a Geiger–Müller (GM) counter was studied by using a decaying source method and tests were performed for two-parameter dead time models including the general models. Activated 56Mn was used as the decaying source and the counting rates were observed in one minute steps for 20 half-lives using a GM probe and a multichannel scaler. Measured data were compared with predictions of a generalized dead time model, a dead time model of nonextending–extending (NE-E) types, and a model of extending–nonextending (E-NE) types in series. The NE–E series model described the measured counting rates better than the other models. The model rates were consistent with the data within 10% up to a true rate of ∼10kcps, however, its application in the region of higher counting rates was limited. Possible causes of this limitation are discussed. For practical purposes, a phenomenological model is suggested to describe measured counting rates above ∼10kcps. [Copyright &y& Elsevier]

Abstract: A high natural radiation zone is investigated for the first time in a geothermal region of Eastern Ghats Mobile Belt (EGMB) of Orissa state in India. The surrounding area comprises a geothermal region which has surveyed using a portable pulsed Geiger–Muller counter. On the basis of findings of GM counter, an area was marked as a high radiation zone. Soil and rock samples collected from the high radiation zone were analyzed by -ray spectrometry (GRS) using NaI(Tl) detector. The radioactivity is found to be contributed mainly by thorium. Concentration of thorium is reported to be very high compared to their normal abundance in crustal rocks. Further, concentrations of 238U and 40K are also high compared to normal abundance in crustal rocks but their magnitude is comparatively less than that of thorium. The average concentrations of 238U (i.e. ), 232Th and 40K are found to be 33, 459ppm and 3%, respectively, in soils and 312, 1723ppm and 5%, respectively, in the granitic rocks. Maximum concentrations of 238U, 232Th and 40K are found to be 95, 1194ppm and 4%, respectively, in soils and 1434, 10,590ppm and 8%, respectively, in the granitic rocks. Radioactive element emits various energies in its decay chain. High energies are utilized to estimate the concentration of actual 238U, 232Th and 40K using a NaI(Tl) detector, however, low energies are used for the same in an HPGe detector. Some of the rock samples (eight in number) were also analyzed using HPGe detector for studying the behavior of low energies emitted in the decay series of uranium and thorium. The absorbed gamma dose rate in air and external annual dose rate of the high radiation zone are calculated to be 2431nGy/h and 3.0mSv/y, respectively. It is approximately 10 times greater than the dose rates obtained outside the high radiation zone. The high concentration of uranium and thorium may be one of the possible heat sources together with the normal geothermal gradient for hot springs present in the region. [Copyright &y& Elsevier]

Abstract: A practical method for the dead time measurement of a counting system is proposed. The method is based on the irradiation of a counting system in the reference photon field for the calibration of dosimeters or dose rate meters. Using the method, we measured the dead time of a GM counting system. [Copyright &y& Elsevier]

The transition to the GM mode in a gas counter has been observed with 5.5 MeV α-rays from 241Am source and a counter using a 30 μm thick anode wire for Q-gas. The pulse height spectra are measured as a function of the applied voltage, from which the gas multiplication curve for Q-gas is derived. The results show that the GM mode jumps from the proportional range. [Copyright &y& Elsevier]

This paper discusses the influence of radiation energy and angle of incidence as possible sources of uncertainties in measurements performed by GM counters. Based on the detection efficiency of GM counters, it has been concluded that the energy of incident radiation does not contribute to the overall uncertainty. The angle of incident radiation does contribute to overall uncertainty, but only in the case of gamma radiation detection. In that case, the uncertainty should be determined by using geometrical probability.