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- Author or Editor: J. Adams x
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Abstract
New circuits are presented to determine precisely the counting losses suffered in the entire gamma-ray spectrometer and to allow automatic correction for them even in the case of time-dependent counting rates as encountered in the measurement of short-lived radioisotopes. Experimental proof is given that the proposed circuitry allows accurate quantitative measurements in gamma-ray spectrometry. With counting rates up to 20,000 cps losses amount to less than 1.5%.
Determination of trace impurities in tin by neutron activation analysis
II. Determination of indium and manganese
Abstract
Two methods are described to determine indium and managenese in high-purity tin. In the first method indium and manganese are separated from the tin and antimony matrix activities on Dowex 1X8 anion exchanger. Tin and antimony are adsorbed in 10M HF while indium and manganese are eluted. In the second method the incident γ-ray intensity due to the tin matrix is reduced by placing a lead absorber between the sample and the detector. The reproducibility and the sensitivity of both methods are of the order of 10 ppb for manganese and of 1 ppb for indium for 1 g samples and a neutron flux of 1011 n·cm−2·sec−1.
Abstract
The use of thermal analysis in studying ancient mortars in English cathedrals is explained. Thermal analysis can be used to investigate both mortar and stone in dated structures. Analysis of ancient mortars show that though recarbonated, they remain soft, yielding to structural deformations. The use of hard (cement mortar) in modern renovation can result in micro-cracking in the stone and subsequent chemical attack from the atmosphere. Contrary to the literature, data developed in the present study suggests that most medieval mortars have reached a near total state of recarbonation.
Determination of trace impurities in tin by neutron activation analysis
I. Determination of arsenic, selenium and antimony
Abstract
Arsenic, selenium and antimony were determined in four different tin samples. After distillation from HBr−H2SO4 medium arsenic and selenium were precipitated with thioacetamide, and antimony was subsequently separated by deposition on iron powder. The separated samples were counted on a high-resolution Ge(Li) γ-spectrometer. The sensitivity of the method is highly satisfactory.
Determination of trace impurities in tin by neutron activation analysis
III. Simultaneous determination of 15 elements
Abstract
A method was developed for the determination of 15 trace elements in tin. High-purity tin samples (99.9999% and 99.999%) as well as tin of technical quality were analysed. Reactor neutron activation of the tin samples was followed by distillation of the matrix activities from a HBr−H2SO4 medium and Ge(Li) gamma-ray spectrometry of the distillation residue. The sensitivity of the method is generally high. For the high-purity samples the detection limits vary from 0.02 ppb (scandium) to 200 ppb (iron) for irradiation of 1 g of tin for 1 week at a thermal flux of 5·1012n·cm−2. ·sec−1. To decontaminate the surface of the tin samples, pre- and post-irradiation etching procedures were applied. The efficiency of these etching techniques was studied.
Abstract
For the determination of very low concentrations of copper in tin, an analytical method involving reactor neutron activation was developed whereby the copper activity was separated from the tin matrix by extraction of the Cu(I) cuproin complex in n-amyl alcohol. A new decontamination technique was sought in order to remove the copper contamination present on the tin surface. Pre-irradiation removal of the tin surface combined with post-irradiation etching appeared to be the most efficient.
Abstract
Abstract
A quantitative separation procedure for210Po in lead has been developed by cupferron and dithizone extraction. The210Po activity is plated on a silver foil for counting with a ZnS(Ag) scintillator, or by α-spectrometry with a surface barrier semiconductor. Different lead samples were analyzed ranging from very old lead with a negligible210Po content to recently manufactured lead samples showing up to 9100 disintegrations per hour and per gram of lead. The reproducibility and the accuracy of the analyses are satisfactory.
Abstract
Neutron activation analysis was applied to the determination of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Lu and Th in rare-earth concentrates resulting from minerals. High-resolution gamma-ray spectrometry with a Ge(Li) detector was used for the non-destructive determination, and a single comparator method using Co as flux monitor was applied.
