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- Author or Editor: K. Masumoto x
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Stable-isotope dilution activation analysis for special samples in which the self-sheilding effect is negligible
Determination of strontium in biological materials by means of photon activation
Abstract
A method has been developed where the element to be determined in the sample consists of at least two stable isotopes, which are easily converted to radionuclides through particular nuclear reactions. The sample is previously processed by adding a known quantity of an enriched isotope of the element, while the comparative reference is prepared by taking an arbitrary amount of the natural element under investigation. The usefulness of the method was verified by photon activation analysis of strontium in standard reference materials of tomato and citrus leaves, using isotopically enriched86Sr as a spike, and the accurary and precision of the method were proved to be valid.
Abstract
A new internal standard method for activation analysis has been developed. This method is characterized by that a suitable element present originally in the sample is used as an internal standard and the comparative standard is prepared by applying the standard addition method to the duplicated sample. When a sample under examination contains Wag of trace element A to be determined together with a known amount of element B which is usable as an internal standard, and when the comparative standard is prepared by adding W a * g of accurately known small amount of the element A to the duplicated sample, even if the sample and comparative standard are irradiated separately by particles with different fluxes, Wa can be determined, easily by using the following equation: Wa=W a * /[(A R * /AR)-1] Where AR and A R * are counting ratios of gamma-rays emitted by two radioactive nuclides produced from the element A and B in the sample and comparative standard, respectively. Neither correction of the inhomogeneities of flux between the sample and comparative standard, nor that of, the self-shielding effects are necessary for the present method. The usefulness of the method was examined through the determination of Co, Ni, Rb and Sr in pepperbush by means of photon activation, and the precision and accuracy of the method were proved to be valid.
Abstract
In order to apply the stable-isotope dilution method to charged-particle activation analysis, determination of strontium in biological materials has been studied by proton activation using isotopically enriched86Sr as a spike. To avoid thermal decomposition of biological materials due to the low penetrating power of proton beam, and to eliminate interfering nuclear reactions due to the matrix elements, strontium in the sample and/or isotopic mixture as a comparator was separated chemically together with most of calcium before bombardment, and the fraction isolated was converted to a silica-gel pellet as a most suitable physical and chemical form for bombardment. By processing as above, it was demonstrated that the strontium contents in the biological materials can be determined accurately, precisely and easily. Through a series of experiments, the method was also proved to be applicable for charged-particle activation analysis.
Abstract
In order to study the application of the new developed internal standard method to charged-particle activation analysis, simultaneous determination of Ti, Cr, Fe, Cu, Ga and Zr in several commercial aluminium alloys has been tried using the respective proton-induced reactions. As a result, it could be proved that the best precision and accuracy are also obtained in these determinations.
Abstract
In order to examine effective applications of the newly developed internal standard method, determinations of Cr, Co, Ni, Zn, As, Rb, Sr, Y, Zr, Nb, Cs, Ce and Pb in three environmental materials, such as pond, lake and estuarine sediments, have been tried by means of photon activation. In these examinations, some major constituent elements in the above sediments were properly used as excellent and effective internal standards. In consequence, it was confirmed that highly accurate and precise determinations of the above 13 elements were achieved easily and favourably.
Abstract
Determination of phosphorus in low-alloy steels by alpha-particle activation analysis has been studied in detail. After thick target yield curves of main interferences produced from the sample were measured as a function of alpha energy, the working standard for the present experiments was provided by applying the internal standard method coupled with the standard addition method under the most suitable bombarding conditions. Using the above working standard, it was demonstrated that the concentration of phosphorus in several low-alloy steels can be determined accurately and precisely by ordinary alphaparticle activation analysis.
Abstract
The combined use of photon activation and γ-γ coincidence spectrometry is described for the useful and selective nondestructive determination of nickel in geological materials. This method is characterized by the utilization of the nuclide emitting β+ particles in its decay and γ-γ coincidence counting with two gates: one for the annihilation photopeak region and the other for the higher Compton plateau region. The practical detection limits by this method for nickel, arsenic, rubidium, sodium and scandium in silicate matrices could be set at 2.0, 1.2, 9.0, 110 and 1.4 μg, respectively.
Abstract
Multielement determinations in the certified reference materials of soils (IAEA soil-5 and 7) have been studied fundamentally by instrumental photon activation analysis using the internal standard method coupled with the standard addition method. For the soil-5 sample, in the first place, the qualities of the comparative standards prepared by two processing methods were compared with each other. As a result, it was demonstrated that a highly accurate and precise multielement determination can be achieved easily by minor improvement in the processing method of the comparative standard to ensure homogeneity. The utility of this processing method for soil samples was proved further through a similar analysis in another soil sample (IAEA soil-7).
Abstract
An automatic gamma-ray spectrometer equipped with a micro-robot for sample changing has been developed and constructed. The facility is comprised of a commercially available micro-robot, sample changer for up to 36 samples, personal computer programmed in BASIC language, input/output devices, detector and multichannel analyzer. This paper describes the components, software and effective uses of the above facility.
Abstract
The spatial distribution of neutrons was measured at the muon science laboratory of KEK by the activation detector method using an imaging plate for the radioactivity measurement. It was confirmed that this method is highly sensitive to detect the average neutron dose of 10 µSv/h. The distribution of thermal and epithermal neutrons was also measured in the experimental room. The cadmium ratio inside the experimental room is one except for the neutron leakage point. The spatial distribution of neutrons inside the concrete shield of KENS was measured by the same method. Aluminum and gold foils were used for the measurement of fast and thermal neutrons, respectively. Two dimensional change of the reaction rate of the 27Al(n,α)24Na reaction shows a good agreement with the results calculated by the Monte Carlo simulation using MARS14 code. Thermal and epithermal neutron flux ratio on the beam axis was measured by the cadmium ratio method. The flux ratios were about 30 and almost constant for every slot except for the surface of the shield, because the cadmium ratio is 2. This method was very useful to measure the activity of many pieces of detector simultaneously without any efficiency and decay correction. Wide dynamic range and high sensitivity are also the merit of this method.
