تصفح Qatar University Science Journal - [From 1981 TO 2007] حسب الموضوع "الفيزياء"
السجلات المعروضة 1 -- 20 من 40
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Analysis Of Al Diffusion In Molten Germanium Induced By Pulsed Nd: Yag Laser Using Sims Technique
( Qatar University , 1996 , Article)In this work the volume diffusion coefficients and profile distribution of Al impurities in molten germanium have been measured using secondary-iron mass spectroscopy (SIMS) technique. Diffusion is achieved with aid of ... -
Analysis of dopant diffusion in molten germanium induced by pulsed nd : yag laser
( Qatar University , 1995 , Article)Laser - induced diffusion of various dopant elements into intransic germanium based on the dipping of Ge into dopant solution, have been used to produce doped ge layer using yag pulse laser with 300us duration ( A, = 1.664(1 ... -
Annealing Behaviour, Tcr Values And Defect Density For "Cold-Condensed" Silver Films
( Qatar University , 1990 , Article)Thin silver films were deposited under vacuum of 10^ -6 Torr by thermal evaporation onto cooled glass substrates kept at low temperatures. Pure argon gas prevailed as residual gas. Annealing behaviour of the electrical ... -
Calculation Of Mass Yield Distributions In Fission Induced By High Energy Protons
( Qatar University , 1991 , Article)An analytical expression is obtained for the mass-yield distribution in fission induced by high-energy protons, using a two-step model. In the first step, the incident proton penetrates the target nucleus, knocking out ... -
Characterization of Polymers in Dilute Solutions
( Qatar University , 1997 , Article)Basic moleculer characterisitics of polymers are: molecular architecture, molecular weight and size, and their distributions. All these characterisitics are derived from measurements of very dilute solutions. Methods of ... -
A comparative study of the mechanical properties of low Density polyethylene (ldpe)
( Qatar University , 1997 , Article)Mechanical properties of engineering polymers which are the most important properties for design and construction purposes are diverse. This has been proved by investigation tensile properties of different grades of LDPE ... -
Design And Implementation Of A Microprocessor Controlled Digital Filter
( Qatar University , 1991 , Article)The construction and implementation of a microprocessor controlled real time recursive digital filter have been given. The system designed could also be applied to a variable coefficients system such as ADAPTIVE FILTER and ... -
Diffuse Phase Transition In Non-Stoichiometric LiRbSO4 Crystals
( Qatar University , 1992 , Article)The influence of changing the ratio of Li2S04 on the structure transition of (RbxLi1-x)2S04 , LRS crystals, where x ranged from 0.1 to 0. 7, was studied by thermal analysis techniques in the temperature range 300 - 600 K. ... -
The effect of doping crystals of tgs with some di- and trivalent ions on its: (i) dielectric constant and a.c. Conductivity
( Qatar University , 1987 , Article)The problem of the existence of a new ferroelectric phase transition at low temperatures in TGS crystals is discussed. The influence of some inorganic divalent and trivalent ions presented in the lattice of TGS on dielectric ... -
The effect of doping crystals of tgs with some di- and trivalent ions on its: (ii) polarization and piezoelectricity
( Qatar University , 1987 , Article)The polarization, coercive field,piezoelectricity and electromechanical coupling for pure and doped single crystals of TGS arp investigated in the temperature range 77-325 K. The influence of the divalent ions Ni 2+, Cu2 ... -
Effects of electric and magnetic fields on the energy levels of a hydrogenic impurity in GaAs/Gal-xAl x As heterjunction
( Qatar University , 1997 , Article)Variational method within the effective — mass approximation is used to calculate the shallow impurities states in GaAs / Gai_xAl^As heteroj unctions. Modified Fang-Howard wavefunction is used as the trial wavefunction. ... -
Effects of the electric field and gamma Radiation on the optical properties of Modified low density polyethylene
( Qatar University , 1997 , Article)The effect of electric field and gamma radiation on the optical properties of low density polyethylene LDPE grade CD 0230 have been studied. The samples were irradiated at gamma doses of 0-100 Mrad and varying electric ... -
Experimental Investigation of the N-Pbs/P-Si Heterojunction Band Lineup with I-V and C-V Measurements
( Qatar University , 2005 , Article)In this paper we present experimental investigation of band lineup of near ideal PbS/Si heterojunction diode using I-V and C-V measurements. The C-V measurements show that the fabricated diodes were abrupt type, and the ... -
Fe57 Mossbauer Study In Cobalt Substituted Magnetite
( Qatar University , 1983 , Article)The Mossbauer effect has been studied in the mixed ferrites CoxFe3_x04 (for x = 0.8, 0.9 and 1) with the spinel structure in the temperature range between 78 and 830K. The composition with x = 1, showed an expected Zeeman ... -
Global And Ultravoilet Radiation Over Kuwait
( Qatar University , 1999 , Article)The data of six spectral bands of solar radiation over Kuwait were measured locally, during the period of time starting May 1, 1995 until February 5,1998. Near ultraviolet spectral band (315-380) nm, shows very week ... -
Impulse Breakdown Characteristics In Air In The Presence Of A Local Spark
( Qatar University , 1996 , Article)In this paper, we study the flashover phenomena in air gaps containing floating metallic objects. The effect of a local spark on the impulse breakdown characteristics of a model gap arrangement which simulating a gas ... -
Integration technique for neutron source standardization inside A cylindrical water tank
( Qatar University , 1993 , Article)This work deals with the evaluation of neutron irradiation facility. Two (Pu-Be) sources and two (Ra-Be) sources are used. Integration technique by a BF3 detector for neutron source standardization is used. The necessary ... -
Ionic Conductivity and Ionic Jump Distance of Nuclear Detectors Group CR-39 and BM-355
( Qatar University , 2000 , Article)Electric properties of two nuclear detectors (CR-39 and BM-355) have been investigated as a function of temperature differences. The conductivity appears to be ionic and it was increased with the temperature increase for ... -
Magnetic Studies on High - Tc Bi - Pb- Sr - Ca - Cu - O Ceramics
( Qatar University , 1997 , Article)The superconducting material with a nominal composition BiI 6 Pb0 4 Sr2 Ca2 Cu3 Ox has been recently synthesized and characterized by the authors using the Q- factor method. The Q-factor data reported in this work shows ... -
Measurements Of Radon Permeability Through Some Membranes
( Qatar University , 1994 , Article)The diffusion of 222Rn through different types of membranes has been studied by an equilibrium method using a Si surface barrier a-detector with a resolution of 14 keV FWHM for ^'Am. The permeability constant for Aluminized ...
