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Abstract  

Various ion beam techniques (E≥1 MeV/amu) are compared from the standpoint of their analytical capabilities: Charged Particle Activation Analysis (CPAA), Particle Induced X-Ray Emission (PIXE), Ion Induced γ-Ray Emission for bulk analysis, Prompt Reaction Analysis (PRA), Rutherford Backscattering Spectrometry for surface layer characterization and ion absorptiometry for microscopic analysis. With CPAA and PIXE≥70 elements can be detected with sub-ppm sensitivity. The scope of CPAA is being extended with heavy ion beams for radioactivation of H, He, Li, Be, B, C isotopes. In surface layer characterization recent developments in PRA and RBS also involve heavy ion beams. In RBS they can significantly enhance mass resolution for M>50 in comparison with α scattering. For example,63Cu and65Cu can be quantitatively identified in surface films using a 1 MeV/amu40Ar beam. In microscopic analysis, the nuclear microprobe can provide atom-specific signals from quantities ≥10−12 g on spots of a diameter ≥2 μm. Ion absorptiometry techniques can sense density variations as low as ±0.5% in 1 μm3 or less of sample volume.

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Professor Richard E. Wainerdi

Presented with the Hevesy Medal for 1977

Journal of Radioanalytical and Nuclear Chemistry
Author: E. Schweikert
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Abstract  

Reaction yields on thick zirconium targets with proton, deuteron,3He and4He activation have been measured and compared. The most favorable reaction combining high sensitivity and selectivity was found to be Zr(p, xn)90Nb. The absolute cross-section for this excitation function has been measured for proton energies up to 20 MeV. Analytical applications are illustrated with nondestructive zirconium analyses in glass. Yields from the thick target experiments indicate that the detection limit for this zirconium analysis method is ∼1 ppb.

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Abstract  

A survey has been made on the application of charged particle activation analysis for the detection of traces of medium Z elements (40≤Z≤58, 72, 74) using protons and deuterons of 20 MeV,3He and4He ions of 40 MeV. The product nuclides considered were γ-ray emitting radioisotopes with half lives ranging from 10 min to 3 days. Based on the thick target yields obtained, proton activation was found to provide an optimum compromise between sensitivity and selectivity.

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Abstract  

This method is based upon the measurement of 3.95-hr43Sc which is formed during α-activation from40Ca, the most abundant (96.8%) isotope of calcium. The excitation function for the40Ca(α, p)43Sc reaction was determined and the maximum yield of43Sc (about 107 cpm per mg of calcium for a 1-hr irradiation at a beam current of 1 μA) was obtained at an irradiation energy of 14 MeV. The interference free sensitivity of the method at this energy was found to be 8.5·10−12 g, for a 1-hr irradiation at a beam current of 10 μA. The elements most likely to interfere with the determination are potassium and scandium. The extent of this interference was investigated as a function of irradiation energy and methods to eliminate or subtract the activity formed from these elements are discussed. An attempt was made to determine non-destructively the calcium content of very pure silicon and aluminium and upper limits for the concentration of calcium in these samples were set at 0.27 ppb and 6.9 ppb, respectively. Magnesium, thulium oxide and yttrium oxide samples of known calcium content were also analysed.

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Abstract  

The scope of NDP can be expanded by measuring (via time-of-flight) the kinetic energies of the recoils emitted from (n,p) or (n,) reactions. When they occur inside a solid, the energies of the emerging recoils reveal depth from which they originated. The Recoil Nucleus Time-of-Flight NDP (RN-TOF-NDP) technique can reveal the depth distribution of some isotopes (e.g.,10B,210Bi) with a resolution of a few Å. Furthermore, it is possible to detect atomic and molecular species ejected at the surface site where the recoil emerges from the solid. This paper discusses the methodology for RN-TOF-NDP and its applications including surface analysis based on atomic and molecular ions codesorbed with the recoils.

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Abstract  

Procedures for instrumental neutron activation analysis have been developed and used on flint samples collected from the Edwards Formation in Texas. Each of the samples was analyzed for Mn, Ca, V, Al, Sc, Co, Fe, As, and K. USGS standard rocks AUG-1, GSP-1, and G-2 were also analyzed in order to test the reliability of this technique. Means and standard deviations of each element determined were calculated. The elemental values ranged from 0.03 ppm for scandium to 1500 ppm for aluminium. Based on relative elemental abundances, the rocks could be classified into two types of flint. This information suggests elemental inhomogeneity in the Edwards Formation.

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Abstract  

A novel method for the characterization of metal containing biological compounds has been developed which utilizes both nuclear activation [e.g.,12C(3He, α)11C] and atomic activations (X-ray emission) induced by 8 MeV3He bombardment. Detection limits for carbon (≈1 μg), oxygen (≈1μg), and metals (1 to 10 ng for elements between P and Zn) were obtained under routine experimental conditions. The metal stoichiometry of six different compounds (alkaline phosphatase, amylase, carbonic anhydrase, diamine oxidase, my oglobin, vitamin B12) were determined with typical relative precisions of ±25% for a 40 μg sample. A comparison of these ratios with carbon and metal measurements obtained by other methods showed a relative accuracy of 1 to 20%.

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Abstract  

The possibility of a simultaneous determination of low and medium Z elements in hair in a single ion beam exposure was studied. Different ion beams, proton, deuteron,3He and18O, at velocities ranging from 2.7–6.9 MeV/amu were investigated. In this work,18 8O4+ beam was found to give the best experimental condition in terms of sensitivity and number of elements detected. The detection limits in a single hair ranged from 2.9·10−5 μg for Fe to 0.72 μg for H using this beam.

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Abstract  

The capabilities of reactor neutron and 12 MeV proton activation were evaluted on samples of orchard leaves, beef liver and bovine liver. Based on γ-ray spectrometry, As, Ca, Cu, Fe, Mo, Pb, Sr, Ti, Zn and Zr at levels ranging from 2 to 20 900 ppm were detected following proton activation of 1 hour. Al, Br, Ca, Cl, Cu, Mg, Mn, Rb and V (ranging from 0.4 to 20 900 ppm) were measured by neutron activation (1 min irradiation). As, Ba, Br, Cr, Co, Fe, Hg, La, Na, Rb, Sb and Zn (ranging from 0.2 to 2400 ppm) were determined following a 14 h neutron irradiation. Although covering different elements, the two techniques are comparable in their scope, i. e. detection limits that can be achieved and number of elements that can be detected simultaneously.

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