Rafidain Journal of Science

Measurement and assessment of dangerosity of X- ray leakage from coloured television (TV) and video display terminals (VDT) are attempted. Three different techniques have been used (X-ray film, scintillation counter and Geiger counter). A comparison of the X-ray film result with literature value is made. Another comparison of the three techniques with published values is also made.
Although big differences are noticed between most of the readings cited in the literature and those found in the present work, it can be seen that all reading are less than the maximum limit of the natural background radiation dose (2 m Sv/y).

Three samples of special lead glass are suggested for radiation protection and radiation shielding. Each one of these samles consist of seven oxides (Lead Oxide, Silicon Oxide, Barium Oxide, Sodium Oxide, Calcium Oxide, Aluminum Oxide and Cerium Oxide) with different weight ratio for each sample.
The mass attenuation coefficient for these samples was theoretically calculated according to Bragg additivity rule for two energies of gamma rays (0.66 and 1.25MeV). The sample which gave higher attenuation coefficient was experimentally manufactured and its mass attenuation coefficient was experimentally measured using (137Cs and 60 Co) and G. M. counter. The results obtained was compared with the mass attenuation coefficient of standard lead glass.

Relative tray transmission factor (RTF) have been determined for two types of trays as a function of field size and source – surface distance (SSD) for Co-60 gamma – ray beam with energy (1.25 MeV). The results show an increase of the relative tray transmission factor with increase field size up to (2.22) and (1.176) for the PMMA tray, and Al tray respectively when the field size is (25 cm x 25 cm) at (SSD = 60 cm(.
This result indicates that the relative tray transmission factor variation with field size is related to a change of the primary photon flounce. Our study also shows that the (RTF) decreases with increasing source – surface distance (SSD) from (60 cm) to (80 cm) for the same type of trays due to a reduced contribution to the total dose from photons scattered in the trays.

This research investigates the effect of the different types of low, middle and high clouds on the intensity of solar radiation received from these clouds in Mosul City during the winter and spring months of the year 2004-2005. The effect of the different types of clouds on the transmissivity of solar beam was studied. The results showed that the transmissivity ranges from 82% for high clouds, from 49% to 55% for middle clouds and from 19% to 21% for low clods. Linear relationships have been established between the transmitted solar radiation under the different types of clouds and the intensity of solar radiation under cloudless skies. These relations were tested using independent data and they gave a good accuracy. The results also showed that low and middle clouds have a serious effect in the reduction of solar radiation passing through it.

In this study a two bulbs system have been designed and constructed we have design and construct to demonstrate the separation of Ethanol – Distilled water liquid operation (50% for each). The operation of separation was checked using the density test and acidity function and calculating the Thermal diffusion factor. The comparison of the result for the same binary mixture but driven from different method (Thermal diffusion column) shows a reasonable agreement.

New models of coil geometry are proposed to energize the single polepiece magnetic electron lens. Systematic studies have been applied to determine the magnetic and optical properties for a set of the lenses of identical parameters but each one is energized by different coil geometry. It has been found that the selection of the proper type of the coil geometry improves the performance of the magnetic single polepiece lens for equal value of the current density.

The effect of pressure on the crystal structure and the transition temperature of the high temperature superconductor YBa2Cu3O7-x (x = 1, 0.5 and 0 ) was studied. Main force of interaction is the electrical interaction because of the ionic nature of these compounds, model of the crystal structure based on experimental data was established. The pressure effect on the above structure was considered, also considered details of ionic position, inter - ionic distances and forces between them. Madelung method used for calculating the forces between the ions and their binding energy. Because Madelung constant reflects the real crystal structure. The effect of pressure on YBCO structure was found via calculating the bulk modulus. The relative volume of YBCO decreases with increasing pressure and oxygen content in the compound. elongation of the Cu(2)-O(4) bond was detected under pressure along the b direction also a change of Madelung energy was found which gives an indication of the effect of pressure on Tc .

Five magnetic electron lenses have been suggested. Each one has round cross section of the iron circuit and of the energizing coil. The axial magnetic flux density distribution and the trajectory of flux lines of these lenses have been studied and the objective and the projector optical properties have been computed as well. The study reveals that these lenses have the electron optical properties different from that of the other lenses of the traditional design.

Infrared spectra of some amphibole minerals show that the absorptivity of the fundamental vibrational OH band is strongly wave number dependent. The investigated have been done on sample include amphibole of termolite,actinolite, anthophylite, grunerite, riebeckite and amphibole asbestos. Spectra obtained from Ca and Fe-Mg amphiboles consist of sharp, well resolved bands. The emphasis on the hydroxyl stretching region, but the vibrational spectra of the silicate anions also discussed.

Optimum total efficiency and output power were derived for Nd:YAG laser with symmetrical resonator configuration, taking into account a new interaction factor called spatial interaction efficiency factor. Under the assumption of the same pumping power and the same resonator losses, the results interacted a lower output power and higher lasing threshold provided that the mirror reflectivity was optimized as compared with a laser system that did not take the spatial interaction efficiency factor into consideration.

Nickel – aluminde coatings were performed on austinitic stainless steel base alloy (321AISI) by packcementation method. Nickel was used as electrodeposition coating before aluminization. Hot corrosion (Sulphidation) behavior of the coatings after exposure in molten salt (Na2SO4) at (884 ºC) were studied under cyclic condition. The Al-rich intermetallic compound was very effective in reducing the corrosion rate in molten salt, while (Ni) or Ni-rich and Fe-rich intermetallic compounds were less resistances. Uncoated stainless steel reveals very poor resistance to Sulphidation in molten salt environment with sever spallation of the protective oxide scale.