This work has been motivated by the need to establish reference materials from locally available sources. Neutron Activation Analysis (NAA) with Ge(Li) detector has been used to determine 26 elements in seven homogeneous clay samples with a wide range of composition. Short half-life nuclides (10s-10 m) were used to assay Na, Mg, K, Tl, Al, V, Mn, Ba, Dy, Ca and U by a fast rabbit transfer system. The long-lived nuclides were used to assay Sc, Sm, Cr, Eu, Ce, Cs, La, Fe, Lu, Hf, Co, Rb, Ta, Sb, and Pa(Th) after decay of24Na. The approach was purely instrumental. The accuracy of the resutls was tested by atomic absorption spectrometriy (AAS).
Prospecting for high grade uranium deposits in NE Nigeria has over the years among other reasons been handicapped by lack of adequate understanding of the elemental primary dispersion pattern associated with known occurrences in this region. Thirty six samples from a low grade uranium occurrence at Gubrunde consisting of disseminated ores and hostrocks were therefore analyzed for 38 elements by NAA, DNAA, EDXRF and flame AAS techniques. The analytical data were evaluated using multivariate statistical techniques. The results show three element groupings (associations). The first group consists of Pb, Ba, Ce, Sm (LREE), that are enriched with increasing uranium concentration in the mineralized zone and are therefore capable of serving as pathfinder elements for uranium. The second group comprising of MgO, K2O, CaO, Na2O and the HREE are depleted in the mineralized zone due to action of hydrothermal fluids and are indicative of altered/mineralized rocks. The third group consists of the rest bulk of elements which feature little or no significant enrichment with increasing uranium but associate with ferruginization (haematite) and possibly refractory minerals.
The mean squared slowing-down distance, <r2>, and the age to themal capture (Migration Area),M2, are direct measures of the slowing-down, and the spreading out, processes of neutrons in a medium. They also enter directly into reactor calculations. These parameters have been determined experimentally for Am-Be neutrons (mean energy 4.46 Me V), in a block of perpex, using the activities induced in thin indium foils from the115In(n,)116In reactions.
Rare Earth Elements (REE's) retain group coherence in their environment and are therefore useful geochemical markers. We report the pattern of ten REE's (La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Lu) determined by Instrumental Neutron Activation Analysis (INAA) for coals obtained from eight mines in Nigeria, namely, Okaba, Enugu, Ogbete, Onyeama, Gombe, Lafia, Asaba and Afikpo. Our results show the existence of fractionations with the highest index of 13.19 for Lafia coal, depletion in HREE, negative Eu anomaly for most of the coals, REE patterns that are consistent with chondritic trends; prominent (Eu/Eu*)cn for Okaba and Gombe coals. Variations in geochemical data observed could suggest strong departures from band metamorphism during the coalification events of the Benue Trough geosynclines, where the coal deposits are all located.
Authors:L. Dim, J. Adetunji, C. Okujeni, S. Elegba, and S. Agaja
Twenty four elements: Fe, Al, Ca, Mg, K, Na, Sc, Sr, Co, Cr, Zn, V, Hf, Ir, W, REE (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu) and Th were determined in limestone and associated calcite from Abakaliki, South-Eastern Nigeria, by instrumental neutron activation analysis (INAA) technique. The USSG reference materials BCR-1 and AGV-1 were included in the analysis to assure quality control of the accumulated data. Hitherto, there is very little work of this type on the deposits in the region being studied. This study, therefore, provides baseline data for the deposit.
Authors:A. Onojah, I. Umar, I. Funtua, S. Elegba, and H. Das
A 5 Ci Am–Be isotopic neutron source was used for the routine determination of manganase in ore samples. Concentration range was 0.1–35%, sample mass is about 17 g, irradiation time 6 h and cooling time 2 min. Counting was performed with a flat 3×3 NaI crystal for 1 h. For low concentrations, several aliquots are irradiated in identical positions around the source and combined. Standards of similar composition to that of the samples are made of KMnO4, mixed with Fe2O3 and SiO2. Corrections are applied for residual differences in neutron and -absorption.
Authors:S. Elegba, K. Usman, S. Ibrahim, T. Ige, S. Nagy, and J. Csikai
Utilization of a sealed tube neutron generator requires the knowledge of the lateral flux density distribution and the mean energy of primary neutrons near to the target. The ion composition of the incident beam is related to the operating conditions of a generator. These parameters have been determined for a KAMAN A-711 sealed tube machine by the foil activation method using different energy and fluence monitor reactions. An analytical expression is also given for the calculation of the relative flux density for a typical geometry.