[en] The radiation attenuation coefficients μ/ρ (cm² g^-1) for concrete and cement samples that used for experimental studies by other researchers were determined by Monte Carlo calculations at 59.5, 80, 356, 661.6, 1173.2 and 1332.5 keV photon energies. The simulated results of attenuation coefficients were compared with the reported experimental data for the same samples and a good agreement has been observed. The intent of this research was to develop a Monte Carlo program useful for various absorbers and energies. The variation of the attenuation coefficient with photon energy has also been investigated for these samples. (author)

[en] We present in this work a detailed design of a small low-pressure chamber outfitted with a ceramic porous plate for evaluating the soil water retention curve (SWRC) in the water potential range from 0 to -100 kPa. The chamber is made of acrylic and permits the use of one unique soil sample each time. The use of this chamber allows quick measurements of soil moisture using nuclear (based on gamma-ray attenuation) and conventional methods and SWRC determinations made with the designed chamber are in agreement with those obtained using a commercial low pressure chamber. The chamber was designed especially for testing the use of the nuclear method as an auxiliary tool for SWRC determinations but it can be easily adapted for routine investigations and a practical alternative for the conventional SWRC method. (authors)

[en] The intensity of radio waves received by radio telescopes is always not subject to human control. In the millimetre band, the propagation of the electromagnetic waves is severely affected by rain rate, dust particle size and drop size in the terms of attenuation, noise and depolarization. At the frequency above 10 GHz, the absorption and scattering by rain cause a reduction in the transmitted signal amplitude which will lead to the reducing of the availability, reliability and performance on the communications link. In this study, the rain effect on radio signal has been investigated. Spectrum analyzer and weather stations were used to obtain the RFI level and rain rate data respectively. The radio frequency interference (RFI) pattern due to rain factor was determined. This will benefit radio astronomer in managing sites for radio observation for radio astronomy purposes. (author)

[en] Attenuation studies on pure elements are straightforward and extensive data sets are available in the literature. However, studies on alloys are meagre due to the nonavailability of alloys of known composition in suitable form. Such studies are useful in estimating effective atomic numbers and to verify the validity of the mixture rule. Empirical expressions for these have been reported in the literature but several discrepancies have been noted. In the present study, transmission experiments were conducted in a narrow beam geometry for the photon energy range 60-400 keV, evaluating the effective atomic numbers for W/Cu alloy of two compositions, 65/35 and 60/40

[en] Radiation travelling through a medium could be attenuated in different ways depending on the type of medium. The research was done on the above basis and was carried out at the Medical Physics department of the National Hospital Abuja using the linear accelerator and an ionization chamber (farmer-type) which served as a radiation detector. The materials used for this research were: the Perspex, concrete, moulded clay (mud), wood, jean material, ordinary material (clothe), cardboard paper, ordinary paper and foam of which each was of (12 x 12 x 1)cm³ except for Perspex which was of (30 x 30 x 1)cm³. They were all beamed at one after the other using energy of 6MV photons from the linear accelerator. The chamber detected the radiation passing through each material and sent it (radiation) in minute current signals to an electrometer which read the signals in milligray. The results obtained indicated that Perspex would best attenuate radiation, but considering its cost, concrete is considered cheaper and next to Perspex from the results and would play a better role.

[en] In this work, mechanical and neutron attenuation properties of thermoplastic natural rubber (TPNR) blends filled with boron carbide (B₄C) have been studied as a function of filler loading. Thermoplastic natural rubber of high density polyethylene/natural rubber (HDPE/NR) blends with different amounts of boron carbide (0-20 wt%) have been prepared via melt mixing method. All samples were subjected to tensile and neutron transmission test. The results showed that tensile strength and elongation at break of the composites were found to decrease with increasing filler loading. On the other hand, neutron shielding performance of the composites were found to improve significantly with the addition of B₄C into TPNR matrix. (author)

No abstract available

[en] The theory, application and measurement of x-ray attenuation coeefficients are discussed

[en] Published in summary form only

[en] Radioisotope technology is commonly used worldwide in process industry and manufacturing plants. The Technological University of Myanmar is exploring applications of nuclear gauges for process diagnostics in the oil and gas industry. A gamma ray pipe scanner is able to detect blockage, sedimentation as well as smooth flow within pipes. The scanner consists of a low activity gamma ray source, NaI(Tl) scintillation detector and Ludlum 2200 scaler ratemeter to investigate the pipe condition. Several experiments were carried out to simulate an actual inspection process and procedure for a medium-size pipe at the Malaysian Nuclear Agency. The inspection results for 10 inch pipe using 2 mCi Ba-133 gamma ray source are reported in this paper. (author)