[en] The amount of cosmic rays varies widely with the altitude, latitude and longitude in each region. In this study, the radiation doses due to the cosmic rays were estimated in two steps: in the first step, the neutron and gamma components of the radiation dose were measured for a roundtrip flight on 3 flight routes (Shiraz-Asaluye, Asaluye-Rasht and Shiraz-Mashhad) using a gamma-tracer photon detector and a Thyac 190 N, neutron detector. The minimum values of the measured gamma and neutron doses of 0.15 and 0.04μSv were measured on the Asaluyeh-Shiraz route at the lowest altitude of 19000 ft, while for Rasht-Asaluyeh route at an altitude of 35000 ft those values were found to be 2.52 and 1.09 mSv, respectively. In the second step, a number of air crew members were equipped with thermoluminescence dosimeters (TLD cards) for evaluating the gamma dose and polycarbonate dosimeters (SSNTD) for assessing the neutron dose for one year. The measured value of the annual effective dose received by the crew ranged between 0.5 mSv/y and 1.16 mSv/y, with an average of 0.9 mSv/y for the gamma component and between 0.37 mSv/y and 0.77 mSv/y with an average of 0.61 mSv/y for the neutron component. The results of this investigation are comparable with the investigations that have been conducted in other countries. For instance in UK, the reported annual effective dose of air crew is about 2 mSv, and in Canada, it is estimated to be between 1 to 5 mSv, depending on the flight situations (such as the latitude and longitude of the cities, the flight altitude, etc).

[en] Polonium-210 (²¹⁰Po) is a natural contaminant of tobacco and its products. Due to its volatility and inherent adsorption properties, ²¹⁰Po is one of the major potential sources of human exposure through smoking. This paper reports measurements on ²¹⁰Po and ²¹⁰Pb levels in domestic as well as imported tobacco to Iran through α-spectrometry technique. The fate of ²¹⁰Po radionuclide has been also followed from tobacco farm through curing procedure in factory. The activity levels of ²¹⁰Po in Iranian domestic and imported cigarettes is found to be on the average as 38.4±0.8 mBq/g with a range of 30.3-51.3 mBq/g and 20.0±0.6 mBq/g with a range of 18.6-21.7 mBq/g, respectively. These levels are considerably higher than those reported in many other parts of the world. In the case of tobacco produced in Iranian northern province of Guilan, drying in closed compartments by fossil fuel and elevated inventories of ²¹⁰Po in soil due to over application of phosphate-rich fertilizers seems to be the main causes of these elevated activity levels.

[en] Uranium deposits of Iran occur mainly in the Central Iran zone. Several uranium deposits have been discovered in this zone. The Narigan area is one of the most important uranium mineralized area in this zone. The uranium bearing sequences in this area are contained in the plutonic to volcanic rocks of Narigan which intruded to the Pre-Cambrian pyroclastics rocks. Plutonic and volcanic rocks are granite, rhyolite and volcanoclastic. Diabasic dykes have been intruded to these igneous rocks. The plutonic and volcanic rocks have been covered by Cretaceous limestones which seem to be youngest the rocks in this area. The aim of our project is to develop a regional exploration strategy for uranium in these igneous rocks. A grid-based sampling was planned following the results of the previous geochemical mapping at a scale of 1:100,000, integrated with geophysical data and alteration zones and outcrop of intrusive rocks. The following results are based on geological, and stream geochemical explorations in 1:20000 scale of this area. During this study 121 samples were collected from the stream sediments of <80 mesh for final sampling. Ten percent of the samples were used for checking laboratories errors. The samples were collected according to conventional methods from 30-40 cm depth of stream sediments. Finally, geochemical and radiometric data were combined and the results introduced 3 anomalies in the Narigan area

[en] In this investigation, the standard type tests performed on the LiF:Mg,Ti chip samples which have been produced in Iran. The dosimetry tests are consisting of sensitivity, homogeneity, linearity, reproducibility, minimum measurable dose, self and residual doses. The obtained results show that some of the tests such as sensitivity, minimum measurable dose, self and residual doses fulfill the criteria given by IEC 61066 and ASTM E668 standards; however, the remaining tests show some discrepancies in comparison with the standards. Also the sensitivity was measured to be 0.92 of that of commercially available TLD-100 (Harshaw) sample. So, the produced LiF:Mg,Ti dosimeter can be used in a routine personal/environmental and medical dosimetry with considering its precision.

[en] Ga-68 is a radioisotope material with a half life of 68 min. As it has a specific decay mode, it is a positron emitter and hence, is popularly used in nuclear medicine. The only way to obtain these nuclides is to produce the mother nuclease which is Germanium-68. There are many nuclear reactions from which the Ge-68 is obtained, however, the best reaction is ⁶9^Ga(p, 2n)⁶8^Ge . The cross section of this nuclear reaction was calculated with the ALICE-91 Code and the result was compared with the practical work made by other researchers, and it was acceptable. Having the cross sections in mind, the best proton energy was calculated to be between 20-25 MeV. Further research showed that Ga₂O₃ is the best type of target material. Therefore, it was necessary to design and make a suitable target holder for these kind of compositions, which for the first time in Iran was demonstrated in the Atomic Energy Organization of Iran. The thickness of the target, bearing in mind the rate of energy loss inside the target material, was calculated with the SRIM Code and the Ga₂O₃ tablets were made with FT-IR facilities at the Nuclear Research Center for Agriculture and Medicine (NRCAM). They were, then bombarded with 22.5 MeV proton energy and the beam currents of 2 and 10 μA. Two weeks after the bombardment the radio chemical separation of Ge-68 was accompolished with concentrated acid HN0₃ and by applying heat. Then, the acid solution was evaporated till dried, after that, an EDTA solution (0.005 M, pH=11) was added to recover the Ge-68. By passing the EDTA solution with the rate of 0.5 ml/min through the AI₂O₃ column, the Ge-68 radioisotope was observed. Then, about 50 ml of EDTA (0.005 M, pH=11) was passed through the loaded column, where almost all the natural Gallium impurities were removed. The prepared generators were milked many times with EDTA solution (0.005 M, pH=8) and the leakage of Ge-68 nuclease and natural Gallium were determined. The average of the mother nuclides (Ge-68) was about 0.03% and the natural Gallium was 0.7 micro gl^-1, which is compatible with the reports of other researchers

[en] In this study, the method of radiocarbon dating was applied to determine the age of fossil shell samples, obtained from southern shores of Iran. The radiocarbon (¹⁴C) dating method has been applied in many fields, including oceanography, geology, and archaeology. In this method the sample is pretreated in physical and chemical procedures, then using a Benzene Synthesis System, benzene (C₆H₆) is synthesized from the sample. One gram of the synthesized benzene is added into a teflon counting vial containing 12 ml scintillator Hisafe3. In order to count and determine the radioactivity concentration of beta particles emitted from radiocarbon, the liquid scintillation counting method is applied. The age determination of fossil samples has been carried out by using count per minute (cpm) values from beta counting of ¹⁴C in synthesized samples comparing to the obtained results from Oxalic Acid Modem Standard. For 8 shell samples studied, the determined ages arc In the range of 110-3890 years, according to Before Present (BP; before 1950). The efficiency of Liquid Scintillation Counting system for ¹⁴C is calculated to be about 92% and the calculation error for the low age samples was ±40 years and for the high age samples was ±100 years, respectively

[en] Nowadays, to mitigate global warming, soil can play a significant role as a pool of terrestrial carbon. Therefore, the objective of the study was to investigate the effect of climate on the radiocarbon Mean Resistance Time in surface and subsurface soils in some of rangelands of Khuzestan Province, Iran. This way, rangelands were selected under different climates in two regions called Izeh and Ramhormoz. In both regions, the control profiles were studied to determine physical and chemical properties of the soil, carbon forms and 1^C(carbon-14 isotopic ratio). The results showed that the Mean Resistance Time of the corresponding depths of Ramhormoz profile (with lower mean annual rainfall) was far higher than those of the Izeh profile, due to higher turnover of fresh organic matters in Izeh rangeland. Unlike Izeh profile, the Mean Resistance Time in Ramhormoz profile did not increase with depth owing to clay content and topographic position of the region i.e. being a depositional site. Overall, the age of carbon-14 in the top orizons of the study areas was mostly affected by factors such as climate, land management and the presence of decomposition sensitive forms of carbon. While, in deep soil the age of carbon was affected y other factors, especially soil taxa, clay content, topographic position (erosional or depositional sites) nd discontinuity in soil parameters such as bulk density than by climate

[en] According to Atomic Energy Organization of Iran Uranium exploration program in Central Iran, Esfordi 1:100,000 sheet which is located in Yazd province, between Bafq and Behabad cities was prospected. The analysis result of the stream sediment samples which were collected by the Geography Society of Iran have been used for radioactive resources of this area. Due to lacking of uranium, thorium and Rare Earth Elements analysis data, the uranium tracers have been used. The data processing, i.e. normalization, univariate and multivariate analysis were studied and ultimately, anomalies maps were prepared. Three uranium potential areas were introduced. These areas include marl and conglomerate sequence in North-west of region. south of Zarigan granite and sandstone sequence with aplites between Esfordi mine and Kooshk mine. Thus, Esfordi sheet is important as a sediment hosted uranium deposit.

[en] In this paper, production of high grade pure graphite in Bonab Research Center is reported. Firstly, we will explain the various graphite production process and the results of crystal lattice analysis such as XRD, density and chemical analysis are proposed. The density of manufactured sample is 1.86 g/cm^3which makes it suitable for many high sensitive technical applications. This is the highest grade purity that has been achieved in Iran. The process of manufacturing and the structural diagnosis of the prepared graphite is explained

[en] Great Kavir basin is the largest inner basin in Iran that extended about 90000 km^2. This basin is situated in the centre of lran , to the south from Alborz mountain range and elongated in the sub- latitudinal trend and its construction is asymmetric. The basin cover consists generally of complicated sequence of continental - marine Oligocene - Miocene molasses. According to drainage systems - conditions, molassoid cycles, alluvial, alluvial - deltaic and lacustrine sediments, climate, morphological conditions and metallogenic and structural features, Great Kavir depression generally is favorable for exigence and surficial uranium deposits (vally - fill, flood plain, deltaic and playa). Uranium occurrences that are Known in the southern and north eastern part of the margent Great Kavir basin, are Arosan, Irekan and Mohammad Abad. Similar geological - structural conditions for uranium mineralization is possible in the margent of Great Kavir basin