مجله علوم و فنون هسته ای
سال سی و نهم شماره 2 (پیاپی 84، تابستان 1397)

Stability analysis of the nuclear structure as a many-body system has a particular importance in nuclear physics. ‎Understanding its statistical properties and also phase transitions provide useful information about nuclear structure and nuclear processes. The statistical properties of the set of energy levels of a system are well described by random matrix theory in quantum chaos. Resonance of energy levels depends on the Hamiltonian symmetry that placed in one of the GOE, GUE, GSE ensembles and in the integrable system in the Poissonian ensemble. The statistical analysis of energy levels by random matrix theory will be possible by calculating the Hamiltonian’s eigenvalues of the system. The calcium chain is an ideal test bench for study on the nuclear structure due to  its existing double magic isotopes. In the present work, we use quantum chaos theory in order to investigate the stability of the nuclear structure of 50Ca and 48Ca isotopes, and the results obtained are compared with those of the Isolde-Cern laboratory.

Experiments utilizing the deep inelastic scattering of leptons from nucleons have been one of the modern tools to understand the complex structure of nucleons in recent and future lepton and hadron colliders. In addition, scattering of polarized leptons from polarized nucleons and polarized light nuclear targets provides us the possibility to probe the spin structure of the nucleon. In this paper, the polarized structure functions of the nucleon are computed using the Jacobi polynomial approach. The effect of considering non-perturbative target mass corrections (TMCs) as well as higher twist (HT) terms are studied at next-to-next-to leading order (NNLO) accuracy. Finally we calculated the polarized light nuclear structure functions for 3He and 3H at NNLO approximation, using the convolution of the light cone momentum distributions with the polarized structure of the free proton and neutron. The stability and reliability of the results are ensured by a detailed comparison with the available and up-to-date polarized DIS data. Based on our obtained results the predictions are in satisfactory agreement with all data analyzed and other phenomenological models in the literature.

Visual inspection of baggage in airports and other critical centers takes a great time. In many cases, especially when the objects inside the load are positioned at specific angles, they may not be detectable by rapid visual examinations. Nowadays, X-ray imaging devices are used to detect objects at the passengers' luggage. Radiographic images obtained due to scattering of photon have a degree of fogging, and sometimes the exact diagnosis of objects is difficult. Image processing methods can improve the contrast and the ability to recognize objects. Different noises and scattering levels exist in radiographic images, which justify the use of automated image processing methods. In this study, Gabor filter and wavelet methods with automatic threshold level have been used to improve the quality of images. According to the results, there is no significant difference in the degree of detection of the objects, regardless of the differences in the reconstructed images. In both methods, the contrast and detection capabilities of the primary radiography images have improved significantly. The computation time of the implementation of the discrete wavelet algorithm is about one eighth of Gabor's time of execution, which can be remarkable given the importance of image processing speed in the area of passenger traffic inspection.

In this paper due to the abundant and also different applications of carbon nanotubes doped with boron, molecular vibrations related to boron element were identified and investigated in B-doped carbon nanotubes by experimental, computational and simulation ‎methods. In the experimental approach, Raman spectra of MWCNTs and B- doped MWCNTs were recorded and the Raman active modes assigned to the relevant specific vibrations. In the computational approach, the vibrational frequencies of C-C and C-B (pure carbon chains and doped with boron) oscillators were simulated using simple harmonic oscillator model and shift of vibrational frequencies toward lower wavenumbers was observed. Finally, by software simulation approach, vibrational frequencies of carbon-carbon and carbon-boron were investigated using the Gaussian software. The D- band intensity increased as the boron concentration reached to 3% while the center of the peak downshifted by 8 cm-1 (1336 cm-1 ® 1328 cm-1). Doping of carbon nanotubes with the boron concentration in the range of 4 to 10% upshifted the D- band central position by 18 cm-1 (1328 cm-1® 1346 cm-1). The ID-IG ratio (the intensity of the disorder D mode divided by the intensity of the graphite G mode) was increased by B-doping of carbon nanotubes (0.75®1.5). In conclusion, the results of the present article reveals that the intensity and frequency variations of D and G modes in the pure and the B doped MWCNT structures were approved with acceptable accuracy by the experimental, computational and simulation methods.

A pair of copper bromide lasers in an oscillator-amplifier configuration was operated to measuring the small-signal gain and saturation intensity, as amplifying parameters of the laser. The values of 0.078cm-1 and 0.07cm-1 were measured for small signal gain with buffer gases neon and helium, respectively, thus, the values of 34 and 47µJ/cm2 were measured for saturation intensity with neon and helium buffer gases, respectively. The output power of system was measured; the values of 8 and 10W were obtained with buffer gases of neon and helium, respectively. It was shown that, the use of helium has more efficient and output power than that of neon in copper bromide lasers. Hence, the optimum conditions have been obtained. The results were compared to that of copper- and gold vapor lasers. The type of buffer gas used can affect the microscopic parameters, which in turn affects the operation and output power of the laser.

Up to now, many studies have been conducted to investigate the role of nuclear energy in reducing environmental costs and climate changes considering the different economic models and energy scenarios in different countries. However, to best of our knowledge, there is no report on this subject in Iran. This study presents a model based on dynamic programming which compares the environmental costs of nuclear power plants with other power plants such as fossil, renewable, gas, steam and combined cycle plants. This model evaluates the impact of external costs in the future planning of electrical energy and by considering baseline and nuclear scenarios, impact studies of external costs are performed. In order to verify the proposed model, the results were compared with the available data and MESSAGE results, and the accuracy of this model was proved. According to this research, nuclear power is an effective strategy for reducing environmental pollution in the future.

The coupled coherent states method (CCS) has been optimized in order to remove the two complexities in the simulation of the ground state of electronic systems. These two complexities are the necessity of the energy restriction in the process of generating CS grid, and the essential refinement of the grid in each time-step. The optimized method which for the first time has been applied for simulation of the potential well of the ground state of one-electron systems such as . The simulation results on the basis of a grid containing only 500 coherent states show a very good consistency with the exact curve. Implementing grids with more coherent states into the simulation would lead to a better consistency with the exact values.

Early Cambrian rhyolite hosts the Choghart iron oxide-apatite (IOA) deposit. The ground radiometric and spectrometric surveys of alteration zone on the margin of the magnetite-apatite ore body show that the radioactive anomaly of thorium occurs in the breccia zone. The chemical analyses of the breccia zone samples by ICP–MS show thorium mineralization. The mineralogical studies by transmitted- and reflected-light microscopey and EPMA indicate that the main thorium minerals in thorium mineralization zone are thorite and sphene. The alteration mineral assemblages related to thorium mineralization of Choghart is consisted of albite ± orthoclase + calc-silicate (actinolite- augite- diopside) + carbonate (calcite) + magnetite + pyrite ± chalcopyrite ± galena + sphene + rutile ± microcline ± apatite (Na-Ca-Fe alteration). The occurrence of paragentic magnetite, pyrite and chalcopyrite with thorite and negative Eu anomaly in the thorium mineralization zone indicate a reduced condition for thorium mineralizing fluids. The similarity in chondrite- and mantle-normalized REE patterns of host rhyolite and the thorium mineralization zone suggests that thorium is originated from continental-arc rhyolitic magma.

Nowadays, due to the suitable decay characteristics and possible production of 68Ga independent of the cyclotron in the form of 68Ge/68Ga generator with reasonable cost, this radionuclide is known as a suitable choice for PET imaging. Recently, SnO2 based 68Ge/68Ga generator was successfully prepared in Iran. In this study, in order to investigate the possible utilization of the made generator in the production and development of 68Ga-based diagnostic radiopharmaceuticals and optimal usage of the generator in the clinical applications, the main characteristics of the generator including the selection of appropriate eluent, elution profile and elution yield were determined, and radionuclidic, chemical and radiochemical purity of the eluate were evaluated. The results of this study indicated that the characteristics of the developed generator in Iran is comparable to those 68Ge/68Ga generators in other countries and it has suitable performance for the usage of developing 68Ga-based PET radiopharmaceuticals.

In this work, a powder with specific chemical and physical characteristics was used and the effect of different additives on grain growth and densification of UO2 pellets were studied. The mixture of powder and additives was pressed and then sintered under hydrogen atmosphere for 6 hours at 1700C. The Cr2O3 additive not only increased densification but also severely increased the grain size. Other additives had little effect on grain growth of the nuclear fuel pellets. Sintering behavior and Coarse-grained microstructure formation are discussed in terms of the reduction of Cr2O3 to Cr, the dissolution of Cr2O3 in UO2 and sintering.