Corrections of HPGe detector efficiency curve due to true coincidence summing by program EFFTRAN and by Monte Carlo simulations.

Standard reference sources, used for efficiency curve calibration of detector, often contain radionuclides with complex decay schemes (such as Co, Y, Eu …), introducing a potential problem in gamma-ray spectrometry, due to the appearance of coincidence summing of detected photons, in particular at a low source-detector distance. In this paper, a set of Monte Carlo simulations of an identical experimental setup were performed in order to obtain the efficiency curve of coaxial p-type HPGe detector for energy region (0-2) MeV, with the effect of true coincidence summing and without it. Obtained efficiency curves are compared with the experimental curve after applied EFFTRAN corrections.

Random coincidence and angular correlation corrections in the sum-peak method using Monte Carlo simulations.

The sum-peak method is a technique for measuring the absolute activity of gamma cascade emitting sources with a single gamma spectrometer. The effects of angular correlations and random coincidences, if not taken into account, can significantly reduce the accuracy of the method. However, we show that Monte Carlo simulations can reproduce the spectral data with a sufficient quality to perform the required corrections.

Search for variations of N22a decay constant.

Exploration of possible anomalies in the decay of different radionuclides is an active research area in the fields of astrophysics and nuclear physics. The most significant changes in decay rates can be expected for β, β or electron capture decay nuclides, due to the proposed influence of the solar neutrino flux by some research groups. In this work, the nuclear decay rate of β decay of N22a was investigated during the time interval of ~33 days.

Estimation of absorbed gamma dose rate from granite by Monte Carlo simulation approach.

Apart from the continuous exposure of humans to background ionising radiation, an increased level of radiation may also originate from the use of building materials with an enhanced level of radioactivity. Thus, it is necessary to examine the content of radionuclides present in building materials, as well as the corresponding dose which may be received by residents from these materials. In this paper, particular attention was dedicated to finding the absorbed dose rate and annual effective dose caused by the presence of naturally occurring radioisotopes Ra, Th, and K in granite, a widely used building material, by means of Monte Carlo simulations.

Simple coincidence technique for cosmic-ray intensity exploration via low-energy photon detection.

Changes in cosmic-ray intensity can significantly influence the search for rare events or processes in nuclear and astroparticle physics through corresponding variations in detector background count rate. In this work, we present an approach to explore cosmic-ray intensity and corresponding cascade production of secondary particles in the detector vicinity using low-energy photon background spectra induced by cosmic rays at the earth's surface. The coincidence system based on a plastic scintillator and an extended range HPGe detector, including a multiparameter device, was used for the acquisition of low-energy photon spectra.

Improvement of in-situ gamma spectrometry methods by Monte-Carlo simulations.

Performing in-situ measurements of gamma radiation originating from soil requires adequate detection efficiency curves, which can be obtained by Monte-Carlo simulations. In simulations, soil density of 1.046 g/cm was used, with the following elemental composition of soil in which gamma radiation was generated: O - 47%, Si -35%, Al - 8%, Fe - 3.

Monte Carlo simulation of beta particle-induced bremsstrahlung doses.

It is well known that protection from the external irradiation produced by beta emitters is simpler than the corresponding shielding of radioactive sources that emit gamma radiation. This is caused by the relatively strong absorption (i.e.

Correlation analysis of the natural radionuclides in soil and indoor radon in Vojvodina, Province of Serbia.

The most dominant source of indoor radon is the underlying soil, so the enhanced levels of radon are usually expected in mountain regions and geology units with high radium and uranium content in surface soils. Laboratory for radioactivity and dose measurement, Faculty of Sciences, University of Novi Sad has rich databases of natural radionuclides concentrations in Vojvodina soil and also of indoor radon concentrations for the region of Vojvodina, Northern Province of Serbia. In this paper we present the results of correlative and multivariate analysis of these results and soil characteristics in order to estimate the geogenic radon potential.

An improved formula for determination of the activity via the sum-peak method.

The sum-peak method principally enables determination of the absolute activity of gamma cascade emitting sources based only on the use of spectral data, without knowledge of the detector efficiencies. However, to achieve better accuracy of the activity results, corrections due to pile-up, accidental coincidences, electronic noise and angular correlations must be introduced into the proposed method. Such corrections usually require the collection of a few gamma spectra and additional extrapolations, thereby further complicating the experimental procedures.

Correlations between soil characteristics and radioactivity content of Vojvodina soil.

During the years 2001 and 2010, the content of U, Ra, Th, K and Cs in agricultural soil and soil geochemical characteristics were measured on 50 locations in Northern Province of Serbia - Vojvodina. The locations for sampling were selected so that they proportionately represent all geomorphologic units in the region. The content of clay and humus varied within wide limits depending on soil type and influence the activity concentrations of radionuclides.

Efficiency study of a big volume well type NaI(Tl) detector by point and voluminous sources and Monte-Carlo simulation.

The activity of environmental samples is usually measured by high resolution HPGe gamma spectrometers. In this work a set-up with a 9in.x9in.

Radon in thermal waters in south-east part of Serbia.

There are several occurrences of thermal waters in the south-eastern part of Serbia, which are originating from igneous and metamorphic rocks. These waters are mainly used in balneology, but some of them are used for drinking purposes and in water supply to heat buildings, for greenhouses and to irrigate land. In this region, there is the well-known Niška banja spa, which has elevated levels of radon.

Investigation of cosmic-ray muon induced processes by the MIREDO facility.

The MIREDO (Muon Induced Rare Event Dynamic Observatory) spectrometer system is primarily developed for the study of cosmic muon induced processes in different materials. Exploration of such interactions can be important for ultra-low background experiments. The system is based on the 100% relative efficiency ultra-low-background HPGe spectrometer.

Radioactivity in the indoor building environment in Serbia.

Measurement of activity concentrations of radionuclides in building materials and radon in indoor space is important in the assessment of population exposures, as most individuals spend 80 % of their time indoors. This paper presents the results of activity concentration measurements of: radon emanated from the soil, radionuclides (226)Ra, (232)Th and (40)K in the soil, indoor radon in the city of Novi Sad (the capital city of Vojvodina) using charcoal canisters and indoor radon in the Vojvodina region using alpha-track detectors and the radioactivity of some building materials. Influences of floor level, space under the rooms, boarding, and the heating system on indoor radon accumulation in the Vojvodina province, situated in the northern part of Serbia, are also presented in this paper.

Different methods for tritium determination in surface water by LSC.

The main aim of this paper was to compare different methods of preparing water samples for tritium analysis by ultra-low-level background liquid scintillation counter, Quantulus 1220. Three methods of sample preparation for low-level tritium measurement have been implemented in the Nuclear Physics Laboratory in Novi Sad: electrolytic enrichment, direct method without electrolytic enrichment and sample Oxidizer 307 method. The examined fresh water samples were rainfall collected during 6 months and water from a stream in the Vinča nuclear research center collected over 3 months.

Airborne radioiodine in northern Serbia from Fukushima.

The results obtained with the monitoring system set up to assess the impact of the Fukushima accident on the environment of Vojvodina (Northern Province of Serbia) are presented and discussed. Aerosol, rain, fresh milk and spinach samples were collected daily in the weeks following the accident. In the aerosol samples, (131)I activity concentrations of several mBq m(-3) were measured, while in rain, milk and spinach samples, (131)I levels had values in a range of (0.

Public exposure to radon in drinking water in Serbia.

Radon is the main source of natural radiation that is received by population. The results of radon activity measurements in water from public drinking fountain, from bottled drinking water and from tap water in the city of Novi Sad, Serbia, are presented in this paper. The measurements were performed by RAD 7 radon detector manufactured by DURRIDGE COMPANY Inc.

Granulation effects on the radon emanation rate.

The radon emanation and the granulation effect on the emanation rate of several building materials (ceramic plates, sand, red brick and siporex brick) with different (226)Ra concentrations were investigated. A ball mill was used to achieve different granulations of the materials. The particle size distributions were determined by a particle size analyser (Mastersizer 2000).

Monitoring for exposures to TENORM sources in Vojvodina region.

TENORM are found in a wide variety of waste materials, some raw mineral ores and in some consumer products (in trace amounts) where molecules of radionuclides may be bound to specific minerals used in the manufacturing process and can result in increases in radiation exposures to workers and the public. The aim of this paper is to understand this problem and to develop effective ways to protect humans and the environment from harmful exposure to the radiation in TENORM materials in the Vojvodina region. The results of measurement of indoor radon concentration in schools and kindergartens and dose-rate and gamma-spectrometry measurements of the workplace with TENORM materials are presented.

Temporal variations of 7Be, 210Pb and 137Cs in moss samples over 14 month period.

Concentrations of (210)Pb, (7)Be and (137)Cs in moss samples were continuously measured, using low-background HPGe spectrometer at Novi Sad, Serbia (45 degrees 14'45''N, 19 degrees 51'35''E). Weekly data collected over 14 month period from January 2007 to March 2008 are presented and discussed. Measured values of (7)Be activity concentrations in dry moss samples are ranged from 201 to 920 Bq/kg showing prominent increase in summer and autumn season.

A new Certified Reference Material for radionuclides in Irish sea sediment (IAEA-385).

A new Certified Reference Material (CRM) for radionuclides in sediment (IAEA-385) is described and the results of the certification process are presented. Eleven radionuclides ((40)K, (137)Cs, (226)Ra, (228)Ra, (230)Th, (232)Th, (234)U, (238)U, (238)Pu, (239+240)Pu and (241)Am) have been certified and information mass activities with 95% confidence intervals are given for seven other radionuclides ((90)Sr, (210)Pb((210)Po), (235)U, (239)Pu, (240)Pu and (241)Pu). Results for less frequently reported radionuclides ((60)Co, (99)Tc, (134)Cs, (155)Eu, (224)Ra and (239)Np) and information on some activity and mass ratios are also reported.

Search for TENORM in the Tisza River sediment.

Sediment samples from the Tisza River in Serbia were investigated for possible TENORM pollutants. The radionuclide content of the samples was determined by means of low-level high-resolution gamma-spectroscopy. In addition to the members of the natural radioactive chains of (238)U and (232)Th and the natural (40)K, Chernobyl origin (137)Cs was detected in 26 of the 28 samples tested.

Indoor radon in rural dwellings of the South-Pannonian region.

The results of indoor radon survey in the South-Pannonian Province Vojvodina (Serbia and Montenegro) are presented. The sampling strategy was oriented towards suburban and urban regions in the Province. For the dwellings typical for such regions the geometric mean annual radon activity concentration of 76.

Pollution of the Begej Canal sediment--metals, radioactivity and toxicity assessment.

The Begej Canal is one among a large number of canals in Vojvodina (Northern Province of Serbia and Montenegro). The paper describes a study of metal and radioactivity contamination of the Begej Canal sediment. It is also concerned with the evaluation of sediment acute toxicity based on standard test species Daphnia magna and simultaneously extracted metals and acid volatile sulfides.

Radioactivity of the Bega sediment-case study of a contaminated canal.

The Bega canal is one among many heavily polluted canals in Vojvodina (the northern province of Serbia and Montenegro). In the framework of the revitalization of this canal, the radionuclide content of the sediment was investigated in order to support the safe deposition after excavation. It was found that, in comparison with the Danube sediment and Vojvodina soil, the Bega sediment is contaminated with (238)U and (137)Cs.