Nuclear and Radiation

Two widely used formalisms based on the cadmium ratio concept (with its associated problems) of the single comparator (k0-NAA standardization) method are used for the multi – elemental analysis at Ghana Research Reactor – 1 (GHARR – 1) facility. This paper examines suitability of GHARR – 1 for reactor neutron activation analysis after the re – configuration of the core by monitoring the stability of the flux parameters f and ? over the course of nine months and the feasibility of using k0 – NAA standardization method based on the Maxwellian neutron distribution concept at the facility for routine analysis. The concepts were validated by analyzing two reference materials. The concentrations of most of the elements were found to be within 10% of the certified values.

The averages concentrations of 238U, 232Th and 40K measured in the samples collected in this study are 130.6±38.7 BqKg-1, 137.9±39.7 BqKg-1 and 1120.1±245.2 BqKg-1 respectively. The absorbed dose rate in air at a height of 1m above the ground surface was estimated. The calculated radiation absorbed dose ranges from 95.4±3.2 nGyh-1 to 300.4±5.5nGyh-1 with an average of 193.2±44.5 nGyh-1 .The effective dose rates were calculated for human exposure to the gamma radiations and were found to be in the range (0.23±0.01- 0.74±0.02) mSv y-1, which is below the ICRP limit of 1 mSv y-1 for members of the general public.

Field experiment conducted to measured Slippage, Effective field capacity, Field Efficiency, Soil Volume Disturbed and Specific Productivity Tillage in silt clay loam soil with depth 18 cm in Baghdad- Iraq. Split – split plot design under randomized complete block design with three replications using Least Significant Design 5 % was used. Three factor used in this experiment included Two types of plows included Chisel and Disk plows which represented main plot , Three Tires Inflation Pressure was second factor included 1.1 ,1.8 and 2.7 Bar, and Three forward speeds of the tillage was third factor included 2.35 , 4.25 and 6.50 km/hr. Result show chisel plow recorded best parameters performance.

The Interacting Boson Model is applied to the even isotopes . Excitation energies, electromagnetic transition strengths, quadrupole and magnetic dipole moments, and ?(E2/M1) multipole mixing ratios, monopole transitions and mixed symmetry states have been described systematically. It is seen that the properties of low-lying levels in these isotopes, for which the comparison between experiment and IBM-2 calculations is possible, can be satisfactorily characterized by the Interacting Boson Model-2.

The study of the physical process of a pulsed laser interacting with human brain tissue is important to identify the energy transport of photons in a strongly diffused zone. The purpose of this article is to describe by a numerical simulation method (Monte Carlo), the light bundle formed by the source-detector pair by scanning a portion of the volume of diseased tissues. In the present simulation, we use the experimental results: the absorption and scattering coefficients respectively ma and ms. We follow the paths of a random walker and we plot for each event as a first step, the relative fluence rate, the reflectance and the transmittance of the signal in terms of respectively depths of penetration and the times expressed in (ps) using a cylindrical geometry. The second step is to study the distribution of the photons of the recorded at different positions, dependent primarily on the ultra-short pulsed laser source in femtosecond wavelength of 800nm. We consider the spherical coordinates (R,q,j) and time t. Thereafter, we compare these results with those calculated with the Cartesian coordinates (x,y,z).

The activity concentrations of natural radionuclides 238U, 232Th and 40K in the cement samples used for construction in Lagos and Ogun State Nigeria were measured by gamma spectrometry using a well-type NaI (Tl) detector. Radiological hazard assessments due to these natural radionuclides were carried out. The average activity concentrations of 238U, 232Th and 40K determined in the samples were 2.16, 7.82 and 114.3 Bq/kg respectively. The mean absorbed dose rate, the mean annual effective dose, excess lifetime cancer risk and annual gonadal equivalent dose in the samples analyzed were 9.59 nGy/h, 17.66 µSv/y, 67.99 (MPY)-1 and 69.07 µSv/y respectively. Values of radium equivalent activity (Raeq), external (Hex) and internal (Hin) hazard indices and gamma activity concentration index (I?) were also estimated. The results obtained in all cases are well below the world average. Therefore, cements produced in this part of the country are safe and considered to have negligible radiological impact on the health of the individuals exposed to them.

In this work different samples of lipsticks were examined using (LIBS) to trace elements in them.

The quest for a versatile standardization method for Instrumental Neutron Activation Analysis Technique has been the major driving force behind many research works for the past few decades. The key factor is the desire to overcome the limitation of dependence on multi-elemental standards without sacrificing analytical accuracy and experimental simplicity. Appraisal of the different approaches towards standardization of Neutron Activation Analysis has been carried out; re-visiting the strengths and weaknesses of each standardization method. k0-standardization method is proposed to be the most suitable for its robustness and for providing remedy to the drawbacks in other methods. The basic principle of Neutron Activation Analysis and the superior qualities of k0-standardization has been reviewed.

It is a well-known fact that solar resource or solar radiation varies spatially as well as temporally across the face of the earth. Hence, resource assessment is a preliminary step for all solar applications. In this study, a flat plate surface solar collector of dimension 2 m2, hinged on a horizontal support for quick adjustment of inclination from 0o to 80o was fabricated and marked out at 0.5o intervals on a telescopic leg graduated in degrees. Measurement of the solar radiation, varying degrees of inclination were taken between 11:00 a.m. and 4:00 p.m. for 7 days of each month at clear sky hours. The measurements were made for five months of the year in Tabriz, East-Azerbaijan Province, Iran. These months selected because they have maximum average solar radiation energy in Iran. At each 0.5 degree of inclination, the solar radiation intensity was replicated three times at each hour and the average value was taken. The flat plate was set truly facing south with an engineering prismatic compass. The result showed that the optimum tilt angle of a flat plate for maximum collection of solar radiation intensities in each month. This work also revealed that the average angle of inclination at which a flat plate surface solar collector will be mounted at fixed position in Tabriz is 31o approximately in studied months. The analysis indicated that when a flat surface was located at the forecasted optimum tilt angle for each of five months, solar radiation intensity was increased, when compared with solar radiation intensity harnessed by the same flat plate collector on other angles and under the same condition. Moreover this improvement impose no extra-cost. Comparison of the measured and calculated optimum values of tilt angle of a flat plate surface for trapping maximum solar radiation intensity for each of five months indicated a high correlation with R2 of 0.98 approximately.

The depth resolution function (DRF) of Secondary Ion Mass Spectrometry (SIMS) analysis has been measured by analyzing delta layers of boron in silicon in different experimental condition using Cameca Ims-6f apparatus. This function has been fitted with an analytical expression initially proposed by Dowsett et al. This is described by three parameters: the rising exponential decay, the standard deviation and the decreasing exponential decay. Physical phenomena related to these fitting parameters are well detailed, in particular, falling exponential decay characterizes the residual mixing effect. The latter is considered the main mechanism responsible for the degradation of the depth resolution in the range of the primary ions energy used in this work. It is shown that when the experimental conditions change, the parameters that govern the analytical expression vary in a satisfactory way. Our depth resolutions are compared with those of the literature. It is shown that our results are in good agreement with those of other authors.