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Abstract  

In this study an investigation into the applicability of the absolute method in Prompt Gamma-ray Neutron Activation Analysis (PGNAA) was undertaken. Although the system parameters are adequately characterized, the scatter in nuclear data for a number of elements is significant. For our particular experimental set up the K-factors were calculated for a number of elements using both Au and Fe as monostandards. A comparison was made between the calculated and experimentally determined K-factors and from this comparison the feasibility of the absolute method in neutron prompt gamma-rays can be realized for a number of elements.

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Abstract  

When a beam of radiation is used as a probe in order to study the elemental composition of an object, the factors involved in obtaining maximum detection sensitivity include target homogeneity, beam uniformity and the solid angle subtended between target and detector. Here we have investigated, both theoretically and experimentally, the significance of these factors in an experimental facility for in-vitro prompt gamma-ray neutron activation analysis and an arrangement used in in-vivo activation analysis. The correction factor to the solid angle, to account for non-uniformity, and the optimisation of reaction rate and solid angle are considered.

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Abstract  

Cement is widely used as a construction material in Libya. Production plants introduce certain contaminants to the environment. The dust from such plants is carried away to neighbouring areas. This dust contains a substantial amount of contaminants depending on the origin of clays used in the production. In this study, a survey of elemental concentration of clay and cement was carried out to assess the environmental impact of such plants, especially those that are situated near residential and agricultural areas. Cement and clay samples, imported and locally produced, were analyzed. Instrumental neutron activation analysis was utilized to determine the elemental concentration of As, Ca, Ce, Co, Cr, Eu, Fe, Hf, La, Na, Rb, Sb, Sc, Sm, Ta, Th, U, Yb and Zn. Elevated concentrations of U and Th were found in a number of cement samples. The two nuclides are part of an elaborate decay scheme producing a range of radioactive elements, which emit alpha-, beta- and gamma-radiation. With 40K, they could give elevated levels of background radiation in buildings resulting in higher exposure doses. This could pose a health hazard and a detrimental effect on the well being of residents, especially in poor ventillated buildings. Also, cement is the main component for constructing underground reservoirs for collecting rainwater for drinking in private residences, so some harmful elements could leach into water. This is the first comprehensive survey of commercial cement brands and clays used in Libya. These results are intended to build a database for trace element concentrations using INAA.

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Abstract  

The paper focuses on the validation of the k 0-method of instrumental neutron activation analysis (k 0-INAA) in the Tajura Nuclear Research Center (TNRC) via the analysis of several certified reference materials. The selected reference materials were: SRM 1572 Citrus Leaves, SRM 1575 Pine Needles, IAEA-A11 Milk Powder, IAEA-V-10 Hay Powder, RM IAEA-Soil-7 and RM IAEA-SL-1 Lake Sediment. The method is based on the PC version Kayzero/Solcoi software package issued by DSM. All the samples, reference materials and monitors were irradiated in various positions of the Tajura reactor with different f and α. The parameters f and α (f — thermal/epithermal neutron flux ratio, α — parameter accounting for the non-ideality of the 1/E epithermal neutron fluence rate distribution) were determined using the bare triple monitor method. The results obtained for all the reference materials are in good agreement with the certified values.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: I. O. Abugassa, S. O. Abugassa, Y. S. Khrbish, A. T. Bashir, K. Doubali, and N. Ben Faid

Summary  

The trace elements composition of gallbladder stones samples of the types cholesterol, pigment and mixed stones in addition to bile have been investigated by k 0-instrumental neutron activation analysis (k 0-INAA). The samples were obtained from several individuals of adult subjects of the Libyan population who undergone open surgery of gallbladder (cholecystectomy) at Al-khadra University Hospital in Tripoli. The samples were lyophilized, irradiated together with Au wire and Zr foil, which serve as flux ratio monitor and a parameter at TNRC. Concentrations of 24 elements in gallstone and 23 elements in bile were determined. The levels of the trace elements in the various samples investigated are measured and discussed. The reliability of the analysis was checked with several biological standard reference materials.

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