[en] The total number albedo and average cosine of the polar angle for water and initial photon energy range from 20 keV to 100 keV are presented in this paper. A water shield in the form of a thick, homogenous plate and perpendicular incidence of the monoenergetic photon beam are assumed. The results were obtained through Monte Carlo simulations of photon reflection by means of the MCNP computer code. Calculated values for the total number albedo were compared with data previously published and good agreement was confirmed. The dependence of the average cosine of the polar angle on energy is studied in detail. It has been found that the total average cosine of the polar angle has values in the narrow interval of 0.66-0.67, approximately corresponding to the reflection angle of 48⁰, and that it does not depend on the initial photon energy. (author)

[en] 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 over all uncertainty, but only in the case of gamma radiation detection. In that case, the uncertainty should be determined by using geometrical probability. (author)

[en] Full text: The high resolution neutron spectrometer with the ³He gas in semiconductor diode coincidence arrangement is used to determine the neutron spectrum at the center of the fast core of the coupled fast-thermal system 'HERBE' at the RB reactor. The neutron spectrum is evaluated from measured pulse-height distribution data by using HE3 computer codes developed in the Vinca Institute. The calculation of detection efficiency, including neutron flux anisotropy and angular distribution of the reaction products in the center-of mass system, is based on a Monte Carlo simulation of entire process neutron detection by ³He(n,p)T reaction in real spectrometer symmetry. Inherent errors in this method of spectrum determination are reduced by calculating the shape of the neutron cross section from the inverse reaction p(T,n)³He. With respect to the discrimination against gamma-pile-up or pile-up of thermal neutron pulses, it was necessary to take into account the effect of the threshold height in geometrical efficiency. determination of detection efficiency is carried out in energy range of interest with maximum statistical errors of results less than 1%. After background subtraction, the measured data are smoothed and efficiency corrections are carried out. The experimental results are compared to the relevant multi-group calculations in the energy range from 1 MeV to 10 MeV. The experimentally obtained spectrum provides a sufficient overlap with the calculated one and no serious divergence is found over measured energy range. (author)

[en] The VINCY Cyclotron is the main part of the TESLA Accelerator Installation at the VINCA Institute of Nuclear Sciences in Belgrade. It is an isochronous cyclotron for the acceleration of both light and heavy ions. The pole of its magnet has the diameter of 2000 mm; its bending limit is 134 MeV, while its focusing limit is 73 MeV. This pa per de scribes the magnetic field measurement sys tem that has been used for the shimming of the VINCY Cyclotron magnet, i.e., for precise shaping of its sectors and plugs. It is an automatic measurement system based on the Hall-probe that moves in the median plane, between the poles of the magnet. We have used this system to obtain precise maps of the magnetic field for different operating regimes of the cyclotron, needed in the process of shimming. The over all measurement uncertainty was estimated to be in the range of ±0.02%. (author)

[en] This paper describes the use of a photostimulable phosphor screen imaging technique to detect radioactive contamination in the leaves of wormwood (Artemisia vulgaris L.) and fern (Dryopteris filix-max CL. Schoff) plants affected by the Chernobyl nuclear power plant accident. The imaging plate technology is well known for many striking performances in two-dimensional radiation detection. Since imaging plate comprises an integrated detection system, it has been extensively applied to surface contamination distribution studies. In this study, plant samples were collected from high- and low-contaminated areas of Ukraine and Belarus, which were affected due to the Chernobyl accident and exposed to imaging technique. Samples from the highly contaminated areas revealed the highest photo-stimulated luminescence on the imaging plate. Moreover, the radionuclides detected in the leaves by gamma and beta ray spectroscopy were ¹³⁷Cs and ⁹⁰Sr, respectively. Additionally, in order to assess contamination, a comparison was also made with leaves of plants affected during the JCO criticality accident in Japan. Based on the results obtained, the importance of imaging plate technology in environmental radiation monitoring has been suggested. (author)

[en] Radiolabelling of antibodies depends on a number of factors including the chemical characteristics of the nuclide and the techniques employed for its incorporation into protein. For preliminary research we used model system and investigate the influence of different factors affecting labelling. Obtained results were successfully used for further radiolabelling of antibodies with different trivalent metals. (author)

[en] Malignant melanoma is a highly aggressive cancer with a poor prognosis due to resistance to radiotherapy and chemotherapy regimens. The mainstay of treatment remains DNA-alkylating agent dacarbazine (DTIC). Fotemustine (FM), chloroethylnitrosourea agent, also has demonstrated significant antitumoral effects in malignant melanoma. However, the resistance of melanoma cells limits their clinical application. In order to enhance the inhibition of melanoma cell growth, in this study, combined treatment of FM and DTIC with proton irradiation, was investigated. We analyzed the effects of combined treatment on HTB140 melanoma cell viability and proliferation. Significant inhibition of cell growth, especially cell proliferation, was obtained after treatment with protons and FM compare to single irradiation or drug treatment. Treatment with protons and DTIC has shown improved growth inhibition compare to appropriate single drug treatment, but not compare to irradiation as a single treatment. (author)

[en] The conditions of the desorption of rhenium from the anion exchange resin Dowex 1·8 by nitric acid were determined. The solution (5·10^-3 mol/dm³ Re in 0.15 mol/dm³ NaCl) was passed through the column containing 0.1 g of the resin. The total sorbed amount of rhenium was 200 mg/g of the resin. It was then eluted by nitric acid in the concentration range of 0.16-7.2 mol/dm³. The most favourable elution profile was found with 3.0 mol/dm³ HNO₃. Over 77% of the total rhenium was desorbed with 5 ml of this eluence. Over 95% of the sorbed rhenium was recovered by using 20 ml of nitric acid in the concentration range of 0.9-7.2 mol/dm³. (author)

[en] Interactions of a TEA CO₂ laser, 100 ns pulse, with titanium nitride (TiN) coating deposited on AISI D2 steel, were studied. The energy absorbed from the laser beam is partially converted to thermal energy, which generates a series of effects such as melting, vaporization of the molten material, shock waves, etc. Morphological modifications of the titanium nitride surface can be summarized as follows: (i) ablation of the TiN coating in the central zone of the irradiated area with creation of grainy and cracked features, (ii) appearance of a hydrodynamic structure like resolidified droplets of the material in the periphery region. The process of sample irradiation was accompanied by the appearance of plasma. Color modifications of the sample, upon laser irradiation, indicate possible chemical changes like oxidation. (author)

[en] Lack of energy is a major crisis of our century; the irregular increase of fossil fuel costs has forced us to search for novel, cheaper, and safer sources of energy. Pebble bed reactors - an advanced new generation of reactors with specific advantages in safety and cost - might turn out to be the desired candidate for the role. The calculation of the critical height of a pebble bed reactor at room temperature, while using the MCNP-4C computer code, is the main goal of this paper. In order to reduce the MCNP computing time compared to the previously proposed schemes, we have devised a new simulation scheme. Different arrangements of kernels in fuel pebble simulations were investigated and the best arrangement to decrease the MCNP execution time (while keeping the accuracy of the results), chosen. The neutron flux distribution and control rods worth, as well as their shadowing effects, have also been considered in this paper. All calculations done for the HTR-10 reactor core are in good agreement with experimental results. (author)