مجله علوم و فنون هسته ای
سال بیست و چهارم شماره 2 (پیاپی 32، تابستان 1383)

Thallium-201 is one of the medical radioisotopes produced in Nuclear Research Center for Agriculture and Medicine via 203Tl (p, 3n) 201Pb reaction, using protons from cyclotron Cyclone 30. Due to high intensity of the neutrons produced from the thallium target and its copper substrate, protection against this radiation is a necessity. The radiation shield is the concrete walls of the target room accessible from outside through a multi-bend maze. In this work, we have calculated the streaming of neutrons through the maze of the target room using MCNP Monte Carlo radiation transport code. The target has been bombarded with 145 µA of 28.5 MeV protons. Equivalent dose rate of neutrons in various positions in the maze has been calculated and compared with the measured values. The maximum deviation between the calculated and measured values is found to occur at the farthest position from the source, namely at the entrance door of the maze, for which the neutron equivalent dose has been calculated as 93 mSv/hr and the corrected measured value upon using the energy spectrum weighted correction factor is 136 mSv/hr. These values are in good agreement with each other according to the shielding point of view.

In this research work, single mode operation based on injection of a CW laser beam into a TEA CO2 laser cavity has been demonstrated. The technique has vast applications in research programs of laser spectroscopy and optical pumping. The observed smooth pulse shapes indicated that the system is operating in a single mode of operation. In addition, the output energy has not been reduced with the laser was operating in a single mode operation on comparison with the case when it is operating in a multi mode regime. Also, no PZT mounted elements or other length stabilization methods were used in order to frequency matching of master and slave resonators.

Labelled vitamin B12 with 58 Co  is one of the important ingredients of the diagnostic Kits for diagnosis of patients affected by anemia. Insufficient absorbtion of vit. B12 is one of the causes anemia in humans and one of the accurate methods for measurement of absorbed vitamin B12 is application ofvit. B12 with radioisotope cobalt – 58 labelled. The isolation and purificationof labelled vit.B12 from fermentation medium of Streptomyces Olivaceus essential process for kit prepration.. The first experiment of this research was isolation and purification with using different resins with solution of cyanocobalamin containing cobalt-59 that was produced by this bacterium.  After investigation and pre-feasibility experiments two non polar resins XAD-4 and XAD-7 were selected. The results of the different experiments on XAD-4 and XAD-7 showed that XAD-4 is much better than the latter one for immobilization of cobalamin. The isolation of vitamin B12 on XAD-4 column was achieved by different solvents such as methanol, ethanol and isopropanol in the different ratio concentrations. The results of TLC (Thin Layer Chromatography) showed that the best eluants solution for desorbtion of cobalamin from XAD- 4 column are solvents such as methanol, ethanol and isopropanol with maximum concentration of vitamin B12 in the range of concentrations 25 up 50 percent, 30 up 40 per-cent and 10 per-cent respectively. Cobalamin was collected in aceton and crystallized in low temprature. .

In the last two decades treatment of brain tumors using BNCT has been performed using improved boron compounds and neutron irradiation techniques. Compounds that make use of carborane clusters, which have a high inherent boron content, should be more effective, provided, of course, the efficient and selective uptake of the boron-containing carrier molecules by cancer or other target cells. Examples of carborane cluster are the icosahedral C2B10H12 carboranes. Many porphyrins and porphyrinoid compounds have demonstrated an ability to selectively accumulate in tumors, and have therefore been considered as the possible candidates for delivery of boron to malignant tissue. The texaphyrins are aromatic pentadentate macro cyclic expanded porphyrins, which have been found to be useful as MRI contrast agents, as radiation sensitizers and in photodynamic theraphy (PDT). In this study, a new boronated texaphyrine for potential use in BNCT has been proposed and synthesized.

One of the important herbicide , for investigation of practical mechanism and studies of metabolism function of different plant, is the 2,4 dichlorophenoxy acetic acid compound .In this article, the production method of its labeled the title compound is explained. In the first step barium [ 14C]carbonate  is converted into potassium [ 14C]cyanide, by using potassium azid at reasonable temperature. Then , after a few synthsis reaction, the compound “ 2,4 dichlorophenoxy methyl iodide is produced via 2,4 dichlorophenoxy, as a starting material. In the next step, the real material as a herbicide: 2,4 dichlorophenoxy acetic acid [carboxy- 14C] is prepared and produced, by coupling reaction  between 2,4 dichlorophenoxy methyl iodide and potassium [ 14C]cyanide , and then hydrolized the resulting nitrile.

DNA in food will sustain damage by gamma radiation that this damage was detected by a sensetive technique called single cell gel electrophoresis. For this purpose poultry and shrimp samples were irradiated by 60Co gamma radiation. The radiation doses for poultry were 2, 5 and 7 kGy and for shrimp were 3 and 7 kGy. Then, irradiated samples were compared with unirradiated ones (control). In addition, the effects of shelf-life and temperature were considered on the same samples. We found that with different doses (even at low dose( identification of irradiated from  unirradiated samples were easily possible.

In this work the design of a target converting high energy electrons to bremsstrahlung x-ray is described. The system has been optimized for different energy of the accelerated electron beam, using the EGS4 Monte-Carlo computer code. For this purpose the thickness of the layers in the target, including the main converter, cooling and lower layer (for the energy spectrum tuning), suitable to the desired and practical conditions have been obtained. In order to evaluate the calculated results, measurements have been carried out for the same geometry using the x-ray converter target, for 2MeV, 5MeV and 10 MeV electron beam. It is shown that the calculated data are in good agreement with the experimental results.

In this article, different types of cyclotron solid targets and their advantages and disadvantages are discussed and a new design is introduced for solid targets of IBA-Cyclone 30 cyclotrons for the first time. In this new targetry, the number and depth of the back grooves for coolant passage were changed. The target material was placed behind an aluminum drawer for bombardment. For this reason the new targetry was named drawer backings. Thus we were able to bombard powders of the target material. These backings have unique capabilities: metallic salts can be bombarded behind the drawer holders and chemical separation may be performed with higher yields and lower costs with respect to other methods. The bombardment may be repeated many times with the same backing. The drawer avoids the presence of contaminant nuclides in the final product.