Journal of Kufa - physics

The buildup factor for gamma ray exposure is most useful in calculations for biological protective shields. The buildup factors for gamma ray exposure were calculated in two layered shields consist of water -lead and lead -water up to optical thickness 20 mean free path ( mfp ) at gamma ray energies 1, 2 and 6 MeV by using kalos's formula. The program has been designed to work at any atomic number of the attenuating medium, photon energy, slab thickness and the arrangement of materials. The results obtained in this search leading to the buildup factor for gamma ray exposure at energies ( 1 and 2 MeV ) in lead-water were higher than the reverse case, while at energy 6 MeV the effect was opposite. The calculated data were parameterized by an empirical formula asa function of optical thickness of two materials. The results obtained were in reasonable agreement with a previous work.

In this study the optical properties of poly vinyl Alcohol (PVA) doped with AliZarin orange Azo dye thin films of different thickness were deposited on glass substrate at room temperature by using cast method technique . The optical properties investigated include their absorbance spectra , transmittance ,absorption coefficient , reflectance spectra ,band gap, extinction coefficient , optical conductivity , refractive index, and complex dielectric constant . theabsorbance of the films were found to be high in the visible region for all the thicknesses with peaks around 400nm , However the absorbance of the films were found to exhibit low values near infrared region . The thickness of the films causes important changes in the optical properties of all parameters were investigated under this study .

Effect of different impurity concentrations that is added during the single crystal silicon solar cell manufacturing on the efficiency of cell has been studied and calculating the theoretical efficiency of the cell( by using theelectronic computerprogramme in visual basic language ), which varied between ( 0.007-3.827) % .The relationship between the impurity concentration and the input parameters in calculating the cell efficiencyhas beenplottedand then plotted the relationship between these concentrations and thetheoretical efficiency of this cellas well as noticing effect of other parameters on that efficiencyand important notes and conclusions is achieved .

In this paper, 170-176Ybisotopes have been studiedby usinginteracting boson model (IBM-1) to determine energy levelsand it wasclassifiedintwo bandsthe ground state and bata bandaddition, thesquare of rotational energy and the moment of inertiavalues for 170-176Yb werecalculated and compared with the experimental data.The obtained results for 170-176Yb werereasonably in good agreement with the experimental data.The attestations referto this isotopes belong to the rotational limit SU(3)

Computer simulation of optical scanning holography (OSH) havebeen developedby (MATLAB-2009). Recording the hologram of an image of type (JPG) wasobtained by taking the fast Fourier transform, fft2,of the original image in the gray scale.Two parts of the recorded hologram were obtained, the real part, called the sine Fresnel zone plate hologram and the imaginary part, called the cosine Fresnel zoneplate hologram. The reconstructed images of the sine and cosine parts are obtained by using the inverse Fourier transform, ifft2. The result is the real image reconstruction of complex Fresnel zone platehologram, Hc+,and the reconstruction of complex Fresnel zone plate hologram, Hc-

The assessment of radiation dose from natural sources is important because natural ionizing radiation is the largest contributor to the collective effective dose received by the world's population. Measured gamma dose rate in indoor and outdoor environments estimated corresponding annual effective dose for some regions in Baghdad city. Indoor and outdoor environmental gamma dose rates were measured using Inspector Exp instrument, in 6 selected regions [A, B, C, D, E and F]. the average dose rates in air resulting from gamma background radiation indoor and outdoor were 121 ± 22 nSv.hr-1and 111 ± 24 nSv.hr-1with range 95 –147 nSv.hr-1 and 80 –150 nSv.hr-1 respectively. Then the annual average effective dose of residents regions was 0.729 mSv

In this study light elements 6Li ,9B for 9B(n,α)6Lireaction as well as α-particle energy from 6.84 MeV to 9.94 MeV are used according to the available data of reaction cross sectionswith threshold energy (3.9537MeV). The more recent cross sections data of 6Li(α,n)9Breaction is reproduced in finesteps (50keV)in the specified energy range , as well as cross section (α,n)values were derived from the published data of (n,α) as a function of energy in the same fine energy steps by using the principle inverse reaction . This calculation involves only the first exited state of 6Li ,9B in the reactions 6Li(α,n)9Band 9B(n,α)6Li .

The importance of refractory materials in various industries such as lining of kilns, furnaces and the need for exploitation of raw materials which are available in Iraqi industries. So this work deal with the exploitation of Iraqi kaolin from Dewechla deposits, as a raw material in the manufacturing of high alumina fire brick.High alumina fire brick specimens (alumina content about 70%) were prepared by semi-dry pressing, then drying and burned at different temperatures 1200,1300, 1400,1500Cᵒfor 2hr soaking time and 100Cᵒ/hr firing rate. Investigations of these specimens show that, the increasing alumina content will increase the strength, the porosity of the fire products, while the hardness, apparent density, water absorption and permanent linear change will decrease. These properties affected by the firing temperature, where the formations of the mullite phase play agoverned role in the behavior and properties of the final products. In addition, the results reveal that the fire brick products appear to withstand thermal shock resistance; it can be used as thermal insulator in various industries.The thermal conductivity and density behavior of products containing alumina ˃ 70% are vary as a function of porosity. Thus, the insulating property of the end product can be improved through the porosity and its distribution.

CdCr2S4) thin film has grown on cleaned glass substrate at (673k) temperature using spray pyrolysis deposition technique of thickness (430nm) . UV-VIS. spectra of the film was studied by using the optical absorbance measurements which were taken in the spectral region from (300-1100)nm . Optical constants such as optical allowed and forbidden energy band gap of direct transition , absorption coefficient , extinctioncoefficient and refractive index were evaluated form these spectra. CdCr2S4has high value of absorption coefficient (α > 104cm-1) which conducive to increasing the probability of occurrence direct transitions .Optical allowed band energy for direct transition was (3.325eV) and the forbidden one was (2.61eV) .

In the present work , the gamma ray buildup factor has been Calculated for ironand aluminumas afixed and moving shieldswith twovelocities ( V1= 16 cm/sec ) and ( V2= 18 cm/sec ) for thicknesses( 0.1 –1 ) cm . by using the scintillation detector NaI(Tl) ( 2′′ x 2′′ ) and tworadioactive sources Cs-137 & Co-60. The effect of the shield movement , its thickness andtheradioactive source energy on the buildup factor has been studied .It wasfound that the buildup factorfor irondecreased with a moving shield , The buildup factor at (V1) velocity wasless than that at (V2) velocity .while , the buildup factor increasedfor aluminum The buildup factor at (V2) velocity wasgreaterthan that at (V2) velocity .The buildup factor increasedwith the thickness of the shield for all studied cases . It was foundthat the buildup factor with Co-60 source was greater with Cs-137source for all fixed and moving cases

The influence of additive coal percentage and its grain size on compressive strength of building bricks were studied .Soil was used as a basic material and coal wasadded to it, with weight percentage of(0.1,0.2,0.5,1,3,5,10)% for three grain sizes. The samples were compressed in cubic shapes of 5cm edge, fired at (1100оC). Porosity , water absorption , lost weight andcompressive strength were calculated for each sample. It was found that there is a close relationship between compressive strength and additive coal percentage and its grain size ,where compressive strength increases for low weight percentage (0.2-0.5)% and fine grain size (75-150) μm and the highest value of compressive strength was recorded with the range of (400kg.f/cm2). On the other hand compressive strength decreases with theadditivecoal and grain size increase where the samples of high percentage of weight (10%) and coarse grain size(300-600)μm has recorded the less value of compressive strength . So the obtained brick has a high quality of Porosity ,water absorption andcompressive strength that the Iraqi standard of qualification No.(25) class A.

The Absorption coefficient of thin films of poly crystal violet (PCVT) was studied at the range of wavelength (200-900) nm, This film was prepared by the cast method. At his study we depended on the radiation process by using Polonium 210 (Po-210) source at the different times (5, 10, 15, 20, 25) min at the distance of 2cm from the samples.The nature of the electronic transitions of these films was studied beside the study of energy gap after and before the radiations. The results show that PCVT has an energy gap at (1.7±0.01) eV for two cases and the transition was direct.This result can be used to improve the physical properties for other types of polymers to use it in a prophylaxis of radiation.