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  • Author or Editor: M. Peisach x
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Abstract  

An overview of prompt nuclear analysis is presented in which the main areas of current interest are described. The various approaches used for measuring concentration profile are illustrated. Some microprobe techniques are referred to, and applications of prompt gamma-ray spectrometry from neutron and charged particle induced reactions are discussed. Topics currently receiving attention are mentioned.

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Abstract  

An activation analysis method has been developed for the routine determination of48Ca. The calcium is chemically separated, converted to the hydroxide, carbonate or chloride and activated for 30 min in the γ-ray flux generated by a primary electron beam between 40 and 57 MeV and a current of about 50 μA. A large number of samples can be activated simultaneously and the ratio of activities of47Ca and43K gives a measure of the isotopic concentration of48Ca. Naturally-occurring44Ca is used as an internal standard. The relative standard deviation is ±3.3%.

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Abstract  

The XSQR technique uses nearly monoenergetic X-rays from the proton bombardment of a primary target to excite X-ray fluorescence for analytical purposes. With the proper choice of primary target, interferences from high concentration components in a matrix may be eliminated. An overview is given of the technique, the equipment it uses and its methodology. The application of the technique is described for the determination of Cr in steels using an Fe primary, Cu and Zn in gold objects using a Ge primary, multielemental analysis of geological and biological materials using primary targets such as Mo, Rh and Pd and Si in oils using a Ti primary target. The method serves as a useful complementary method to PIXE for the determination of the medium mass elements.

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Abstract  

Triton-induced reactions on oxygen were studied with a view to using the prompt γ-rays for analytical purposes. Five γ-rays were found to be potentially useful, of which three had a high intensity, the n(1, 0), n(2, 0) and p(1, 0) γ-rays, the other two being the n(3, 0) and the unresolved pair α(1, 0)–α(2, 0). The γ-rays are labelled according to the conventions(a,b), wheres is the light prompt product and the γ-photon is emitted by de-excitation from levela tob in the heavy product nucleus. The method had a relative precision of 2 to 3.5% for surface oxygen concentrations from 50 to 3 μg/cm2. The sensitivity with 1 900 keV tritons was 0.13 μg/cm2 on surfaces of steel or copper which did not yield interfering γ-rays, but 0.45 μg/cm2 on aluminium where interfering γ-rays were emitted.

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Abstract  

The energy spectrum of alpha particles scattered from a beam of 4 MeV was used to determine heavy elements and oxygen and silicon in glass. Simultaneously, but with a separate detector, the energy spectrum of prompt protons from (α, p) reactions were used to determine boron, sodium and aluminium. Both detectors were placed at 135° to the direction of the beam, but the proton detector was covered with an absorber to stop backscattered alpha particles, Glass samples analysed by other methods and standard glass powders from the U. S. Bureau of Standards were used as references.

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Abstract  

The role played by national institutes and universities in the education, training and research in South Africa, is described. In addition, details are given of the nuclear science courses available at technikons for students in chemistry, physics, nuclear technology, and analytical and medical applications.

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Abstract  

An assessment was made of the analytical potential of the exoergic reactions on boron, induced by3He+ beams. Possible interferences from C, N and O were studied. Gamma-rays originating from (3He, n), (3He, d), (3He, d), (3He, ) and Coulomb excitation were identified. Possible practical applications in boron studies are indicated.

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Abstract  

A recently discovered phenomenon of excessively high X-ray production is discussed. The high yield is attributed to the build-up of potential on non-conducting targets irradiated with accelerated ion beams, and the subsequent discharge. Ion-beams of1H+,1H2 +,2H+,2H2 +,3He+,3He2+,4He+,14N+,14N2+,16O+ and20Ne+ were used. A new mechanism of X-ray excitation is proposed. The increased X-ray fluxes produced by this process are suitable for analytical applications of high specificity. The mechanism of excitation associated with the process, factors affecting the high X-ray yields, applications and a general overview of the studies undertaken with the various ion beams are given.

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Abstract  

Earlier work on Charge Induced X-rays (CHIX) was extended to include the X-ray energy region between 0.70 to 4.0 keV. Protons of 700 keV, and1H 2 + ion beams of equivalent proton energies in the range 350–450 keV were used to produce enhanced yields of L and MX-rays from a suitable selection of highly compacted non-conducting samples. Enhancement factors are given and possible applications are mentioned.

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