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.