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Rare earth elements and valuable elements within Mkuju uranium core samples were analysed using EDXRF. Mean elemental concentrations for selected elements including Al, P, K, Ti, V, Mn, Fe, Y, Mo, Ag, Ba, La, Ce, and U were determined as 96445.79 μg/g, 547.19 μg/g, 25296.88 μg/g, 5926.33 μg/g, 116.26 μg/g, 455.02 μg/g, 60.1 μg/g, 142.34 μg/g, 15.8 μg/g, 493.98 μg/g, 67.53 μg/g, 118.68 μg/g, and 128.37 μg/g respectively. The Rare Earth elements: Y, La and Ce and valuable elements: Mo, Ag and U have enrichment factor of EF >1.5 which indicates that, these elements were formed from rocks through geological processes and can be mined at a profit. The valuable elements AL, P, K, Ti, V, Mn, Fe and Ba have enrichment factor of EF ≤ 1.5 which indicates that, these elements were formed from natural weathering processes. It is concluded that, despite the low concentration of the Rare Earth and valuable elements, the possibility of recovering both valuable and Rare Earth elements in Mkuju deposit is significant. [ABSTRACT FROM AUTHOR]

In this study, a reduced size neutron long counter with improved response function was designed using SuperMC simulation code. The main parts of the reduced size long counter are 3He proportional counter, cylindrical moderators made of polyethylene, chromium metal converter, neutron absorber material and outer aluminum cover. A 1.5 cm thick layer of chromium metal was embedded into the hydrogen-rich moderator to enhance response of the long counter at high neutron energies. The radius and length of the long counter was reduced to 15 cm and 35 cm, respectively. In this design we managed to obtain a flat response function from a few keV to 20 MeV energy range. The angular response function, determined at 0.5 MeV and 14 MeV neutron energies, confirmed that the reduced size long counter designed in this study is not significantly affected by in-scattered neutrons. The reduced size long counter is suitable for use as a standard transfer instrument for monitoring neutron fluence in mono-energetic neutron fields.

Determination of the concentration of heavy metals in tea leaves is important in assessing its quality for human consumption. This study aimed to assess the relationship between the concentration of heavy metals in soil and tea leaves at Kwamkoro tea plantation in Amani, Tanga. The soil and tea leaves samples were analysed by using the Energy Dispersive X-Ray Fluorescence Spectrometry. The results of heavy metals mean concentrations in soil were Cr (185.65 ± 27.91 µg/g), Mn (341.15 ± 24.41 µg/g), Ni (25.6 ± 3.27 µg/g), Cu (21.71 ± 2.33 µg/g), Zn (41.29 ± 5.27 µg/g), As (1.25 ± 0.17 µg/g), Cd (2.47 ± 0.53 µg/g), Hg (1.06 ± 0.21 µg/g) and Pb (17.65 ± 2.35 µg/g). Mean concentration of As and Cd in soil of Amani, Tanga were 1.25 and 2.47 times greater than the maximum permissible limit values for agricultural soil set by the Tanzania Bureau of Standards. The mean concentrations of heavy metals in tea leaves were Cu (15.19 ± 0.62 µg/g), As (0.03 ± 0.03µg/g), Cd (1.88 ± 0.68 µg/g), Hg (0.10 ± 0.04 µg/g), and Pb (0.41 ± 0.11 µg/g). The mean concentrations of Cu, As, Hg and Pb were below, while that of Cd was above the limit value of safety standard set by the WHO and FAO. The study concluded that, the strong positive correlation observed between heavy metals in soil and tea leaves implies that there is strong relationship between the concentration of heavy metals in the soil and those found in tea leaves. Therefore, the application of phosphates fertilizer and agrochemicals must be monitored in Amani tea plantation because it increases the concentrations of heavy metals in both soil and tea leaves. [ABSTRACT FROM AUTHOR]

We have designed an extended range neutron long counter on the basis of work optimized using SuperMC code. The problem of the existing traditional long counters is that their response function falls rapidly above 5MeV. We proposed a new designed by adding two layers of converter material inside the polyethylene moderator. The relatively low density chromium and high density lead metals convert high energy neutron by (n, xn) spallation reaction. This produces more neutrons of lower energies, which have higher probability of being detected by thermal ³He-counter. The response function at lower neutron energies was improved by inserting small polyethylene cylinder in front of ³He counter. In this design we achieved to extent the flat response function of the long counter from few keV up to 150MeV. The total fluctuation of response curve is less than ±9% over the entire energy range. The designed long counter is suitable to be used as neutron monitor for monitoring neutron fluence at high-energy neutron source. [ABSTRACT FROM AUTHOR]

A low-sensitivity neutron long counter was designed as a standard directional flow detector to monitor neutron fluence reference values of an accelerator-based 14-MeV D-T neutron source with yield of 1013 n s-1. The energy response over 6 MeV was improved using a tungsten radiator, which acts as an energy converter via the (n, xn) reaction. Different parameters were optimised to flatten the neutron energy response over a wide energy range. A simulation of the designed neutron long counter was performed using the Monte Carlo codes SuperMC. The response function is relatively flat in the energy range of 1 keV-20 MeV. The results show that the maximal relative variation is ∼7.8 %. [ABSTRACT FROM AUTHOR]

A low-sensitivity neutron long counter was designed as a standard directional flow detector to monitor neutron fluence reference values of an accelerator-based 14-MeV D-T neutron source with yield of 10(13) n s(-1). The energy response over 6 MeV was improved using a tungsten radiator, which acts as an energy converter via the (n, xn) reaction. Different parameters were optimised to flatten the neutron energy response over a wide energy range. A simulation of the designed neutron long counter was performed using the Monte Carlo codes SuperMC. The response function is relatively flat in the energy range of 1 keV-20 MeV. The results show that the maximal relative variation is ∼7.8 %., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)