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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  

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  

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  

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  

An activation analysis method has been developed for the routine determination of43Ca. The calcium is chemically separated and converted to fluoride. When activated for 2 hours with 4.50 MeV protons,43Sc and48Sc are produced and the ratio of their activities is a measure of the isotopic concentrations of43Ca.48Ca serves as an internal standard to represent total natural calcium. The relative standard deviation is ±1.5% and the method can determine a change of +0.004 atom %43Ca in natural calcium.42Ca may interfere, if present in enriched concentrations.

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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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Abstract  

Previous studies reporting “abnormally” high X-ray yields from non-conducting targets under bombardment with low energy ion-beams were considered to be charge related. These studies were extended to metal targets surrounded by insulating material. Differences and similarities are discussed.

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Abstract  

Three different proton-induced reactions were used to analyze 19 pure lithium compounds of known composition. Prompt alpha-particles were measured from the reaction7Li(p, )4He at Ep=4.5 MeV and prompt gamma-rays of 429 and 479 keV from the ractions7Li(p,n)7Be and7Li(p,p )7Li, respectively, at Ep=4.5 MeV. Elemental stopping powers were calculated from tables and used to compute the stopping power of the target matrices by Bragg's Law. Apparent discrepancies in the measured yield could point to deviations from Bragg's Law and hence to molecular effects. The maximum value for any molecular effect was found to be <5.5%.

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Abstract  

The use of alpha backscattering is described for the study of oleo-resinous lacquers on tinplate. The lacquer composition is measured as a function of curing temperature, duration of stoving and ageing. The effect of reheating understoved specimens is evaluated and the decomposition during alpha bombardment is measured. The use of prompt proton spectrometry from (d, p) reactions is described for the analysis of stains on tinplate surfaces produced by interaction with protein-rich foods.

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