Beryllium chemical combination has a considerable effect on the design and fabrication of the 241 Am -9 Be neutron source. In this investigation the beryllium combinations were studied as a generator of neutrons with various mass percentage, and the neutron yields were also calculated using the results of the ALICE and SRIM codes calculations per unit incident charge. The neutron yields of Beryllium Hydride, Beryllium Carbide, Beryllium Hydroxide, Beryllium Oxide, Beryllium Acetate, Beryllium Acetylacetonate and Beryllium Sulfate were calculated as 4397.992 ´ 10-7, 1511.184 ´ 10-7, 976.609 ´ 10-7, 595.299 ´ 10-7, 336.163 ´ 10-7, 169.62 ´ 10-7and 149.053 ´ 10-7respectively. Our calculations indicate that, the Beryllium Hydride is a proper material for use in the241 Am -9 Be neutron source.

In this study, a general theoretical model to foresee and calculate the current-voltage characteristics in a plateau zone and the associated efficiency of the neutron detector (sensitivity) is presented.This study is to complete the previous studies in this field. The model also considers electric field distortion resulting from the charge collection effect. The characteristics curve is obtained as a function of fission rate, chamber geometry, and filling gas pressure. The output current at the saturation domain is calculated. The applied voltages about two phenomena, recombination and avalanche, for working the chamber in an ionization zone are an important part of the calculation. In developing the theoretical model, the MCNP code for fission rate, the SRIM code for electron-ion pair and GEANT4 for gamma sensitivity calculations were used.

Background: Iodine-123 (123I) is regarded as one of the best radionuclides for in vivo medical studies using single-photon emission computed tomography (SPECT) due to its suitable physical property. Materials and Methods: To design a new system in order to replace cryogenically solidified xenon target by the gas one, some necessary calculations are needed to be done such as finding the excitation functions variation of the production reactions, thick target yield of 123I production, etc. The computer codes Alice91 and SRIM have been used as a calculation tools. Results: According to the suggested design, a conical shaped irradiation vessel made of copper with thickness of 1mm, outlet diameter of 1 cm, 5 cm length and 12° angle at summit can be fixed inside a liquid nitrogen housing chamber. The 124Xe gas was sent to the inside of this very cold conical trap and eventually deposited on its surface in solid form. Calculation showed that during bombardment with 17- 28 MeV proton energy, the thickness of solidified xenon layer remained about 0.28 mm. Conclusion: The production yield of 123I can be predicted to be around 150 mCi/mAh. Iran.

Background: High-velocity carbon ion beams represent the most advanced tool for radiotherapy of deep-seated tumors. Currently, the superiority of carbon ion therapy is more prominent on lung cancer or hepatomas. Materials and Methods: The data for lateral straggling and projected range of monoenergetic 290 MeV/u (3.48 GeV) carbon ions in muscle tissue were obtained from the stopping and range of ions in matter (SRIM) computer code. The data were transformed to determine the carbon ion trajectories in tissue by means of the Monte Carlo method. Consequently, the lateral dose distributions in the Bragg peak as well as the thickness of a thin discshaped tumor in the lateral direction were computed. The absorbed dose in the tissue was obtained as a function of the diameter of a carbon ion pencil beam. Results: More than 90% of the radiation dose in the lateral direction is deposited in the Bragg peak. The simulation results are in agreement with the existing data. Conclusion: It was confirmed that this method is reliable for estimation of dose deposited in human tissue by carbon ion beams.