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Abstract  

The instrumental neutron activation analysis technique (INAA) was used in the qualitative and quantitative analysis of 48 geological samples from the Umm Al-Birak area in the Kingdom of Saudi Arabia. The samples were properly prepared together with their standards and simultaneously irradiated in a neutron flux of 2.4 ·1012 n·cm–2 s–1 in the reactor facilities of the National Tsing Hua University (THOR) in Taiwan. Gamma-spectra from the high resolution Ge(Li) detector were analyzed using the BRUTAl code. As a result of the analysis of the geological samples, 20 trace elements were identified qualitatively and quantitatively. These elements are: Co, Cr, Eu, Fe, Hf, K, La, Lu, Na, Rb, Sc, Sm, Ta, Tb, Th, U, Yb, Zn and Zr. The concentrations of these elements have been used in the investigations of the geochemistry of the Umm Al-Birak microgranite site using the BMDP computer code of the Ministry of Petroleum and Mineral Resources. This investigation showed that the high grade area is a differentiated rock that crystallized in a late stage of the Umm Al-Birak microgranite area.

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Abstract  

14 MeV absolute neutron activation has been tested for the elemental analysis of steel alloys. Important factors such as cross-section, neutron energy, efficiency and sources of error are discussed. The elements which could be detected with good statistics for steel and iron pipe segments were Fe, Cr, Ni, Si and Mo, and detected with low statistics were Nb and Mn. In spite of the large interference and high Fe contents the precision was about 5% except for the elements Mn and Nb which were 14% and 20%, respectively. In the standard reference material, accuracy was better for Fe, Cr, Mo, Ni and poorer for Mn and Si.

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Abstract  

An automatic activation analyzer with sample changer, pneumatic transfer system and fast pulse counting with real time pulse pile-up and dead time compensation is described. Transfer times between 80 and 300 ms from irradiation position to measurement station can be obtained. Counting losses are corrected within 10% up to total count rates of 120 kc/s.

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Abstract  

The chemistry laboratory at the Peruvian Institute of Nuclear Energy (IPEN) has carried out a validation method for the samples of siliceous composition. At least seven variables affecting the robustness of the results were initially identified, which may interact simultaneously or individually. Conventional evaluation hereof would imply a massive number of analyses and a far more effective approach for assessment of the robustness for these effects was found in the Youden-Steiner test, which provides the necessary information by only eight analyses for each sample type. Three reference materials were used for evaluating the effects of variations in sample mass, irradiation duration, standard mass, neutron flux, decay time, counting time and counting distance.

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Abstract  

In April 2007 the new nuclear research reactor, OPAL, was opened at Lucas Heights in Sydney. OPAL is a 20 MW open pool light water reactor with a heavy water reflector vessel and contains a cold neutron source. It is a multi-purpose facility for radioisotope production, irradiation services and neutron beam research. The OPAL design includes purpose-built facilities for instrumental neutron activation analysis (INAA) and delayed neutron activation analysis (DNAA). For INAA there is a short residence time facility in a neutron flux of around 2·1013 cm−2·s−1 and a number of long residence time facilities providing fluxes from 3·1012 to 1·1014 cm−2·s–1. The flux at the short residence time DNAA facility is around 6·1012 cm−2·s−1. The main focus for INAA at OPAL is the research community, meeting the needs of a wide range of disciplines, including mineral processing, geology, the environment, health and archaeology. Both the relative (comparator) method and the k 0-method of standardization for INAA are being established in OPAL. A description of progress, plans and capabilities are presented.

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Abstract  

Between 8th July 2002 and 18th June 2004, aerosol samples were collected in Azores. Their inorganic composition was obtained by neutron activation analysis in order to study the differences of aerosols in two atmospheric altitudes of the central north Atlantic: (1) PICO-NARE observatory (Lower Free Troposphere-LFT) at Pico mountain summit (38,470ºN, 28,404ºW, 2,225 m a.s.l.) in Pico Island, Azores, where air masses from the surrounding continents (Africa, Europe, Central and North America) pass through, carrying aerosols with anthropogenic (Sb, Br, Mo, U, Se and Tb) and/or natural emissions (Fe, Co, La, Na, Sm, Cr, Zn, Hf, K and Th); (2) TERCEIRA-NARE station (Marine Boundary Layer) at Serreta (38,69ºN, 27,36ºW, 50 m a.s.l.), in Terceira Island, Azores, where natural aerosols (I, Cl, Na, Br and other soil related elements) are predominant. However, a combined interpretation of the data points out to a co-existence of the anthropogenic elements Sb and Mo, eventually with similar origins as the ones passing Pico Mountain summit. Very high concentrations and enrichment factors for Sb, Mo and Br in LFT, higher than the ones found in other areas, confirm atmospheric long-range transport mainly from the west boundary of north Atlantic; this may indicate eventual accumulation and persistence of those elements in the area due to the presence of Azores high pressures or the Hadley cells effect. A significant correlation between Fe and Yb and the enrichment of rare earth elements (La, Sm, Tb and Yb) and Th in LFT aerosols, both reflect a mineral dust intrusions from north Africa (Sahara and Sahel region).

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Journal of Radioanalytical and Nuclear Chemistry
Authors: L. Cao, J. Hattrick-Simpers, R. Bindel, B. Tomlin, R. Zeisler, R. Paul, L. Bendersky, and R. Downing

Abstract  

Cold neutron prompt gamma activation analysis (PGAA) was used to determine the mass of hydrogen in Mg hydride thin films with varying hydrogenation times. The results suggest that hydrogenation of the Mg thin films remains unsaturated even after 48 h of treatment, contrary to the indications of inferential hydrogen measurement methods. To demonstrate PGAA as an effective combinatorial methodology for hydride thin films, a continuously varying composition gradient of thin MgyTi(1−y) hydride film with y ranging from 0.65 to 0.94 was prepared and analyzed by both PGAA and instrumental neutron activation analysis (INAA). The variation in the molar ratio of Mg, Ti, and H was obtained for nine 5 mm wide segments of the film.

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Abstract  

Major and trace element contents in iron ore reference materials were investigated using k 0-instrumental neutron activation analysis (k 0-INAA). To avoid iron interferences, radiochemical separation was developed (k 0-RNAA). The determination of the investigated elements in the inorganic phase from hydrochloric acid solution was performed after radiochemical separation of iron by diisopropyl ether. It was found that after the Fe elimination, the limit of detection for some elements was much lower that enables their direct determination. The distribution of 39 elements (with intermediate/medium and long half-life radionuclides) after Fe removal was investigated.

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Abstract  

Neutron activation analysis of Se in urine reaches an optimum sensitivity (few ppb) and precision (±12%) when the traces are complexed without using a carrier by ammonium pryrrolidindithiocarbamate (APDC) at pH 1.5–2 and adsorbed on activated carbon filters. In this way the selenium traces analysis have been carried out through77mSe in 45 urine samples on a pre-separation basis by cyclic activation ofthe carbon filters. The selenium concentration in our blanks is virtually zero, because APDC proved to be selnium free and selenium mass in 50 mg of activated carbon used as a filter is 20 times below our qualitative detection limit and 144 times below our quantitative detection limit. The samples were first of day urine from healthy and ill women suffering cervical uterine cancer, at different evolution stages: incipient, intemediate and advanced, with no treatment, and surgery, radiotherapy, chemotherapy, or a combined treatment. The results show a consistent tred to increase the selenium trace concentration during the intemediate stage, whereas it is the same than nomal for incipient cases, and it decreases to the lowest concentrations for advanced cases.

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Abstract  

In this preliminary study, scalp hair samples from 36 individuals resident in Sofia, Bulgaria, were analysed and Ag, Al, As, Au, Ba, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, F, Fe, Hg, I, K, La, Mg, Mn, Mo, Na, Ni, Rb, S, Sb, Sc, Se, Sn, Sr, Ti, V, W, and Zn were determined. Instrumental neutron activation analysis (INAA) methods were used. Three washing procedures.: distilled-deionised water; acidacetone-water; and Triton X-100 detergent-water, showed a variable elemental change strongly dependent on the procedure used. More than 18 elements (Al, As, Ba, Ca, Ce, Cl, Co, Cs, F, Fe, I, K, La, Mo, Na, Ni, Sb, Sc, Sr and V) were easily removed by water-washing. Triton X-100 detergent was more effective in removing Ag, As, Au, Cl, Cs, K, Na and Rb; but not Hg. Only S and Zn were strongly incorporated in the hair structure (less than 10% being removable by any washing technique). There is no significant age correlation with any element between the various hair treatment groups. Elevated cadmium levels were found in the hair of smokers (0.711–4.913 g/g Cd) compared with nonsmokers (0.568–2.681 g/g Cd). Comparison of the elemental data for distilled water-washed hair and studies from Oxford, England and Hastings, and Hastings, New Zealand (using the same INAA method) revealed interesting variations dependent on local industrial and nutritional factors.

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