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- Author or Editor: R. Wainerdi x
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Abstract
A technique for using internal standards in the determination of Si in rocks using fast neutron activation is presented. Different weights of barium acetate were irradiated for 30 seconds then cooled for 10 seconds before counting for one minute. A peak area, at 0.662 MeV due to137mBa, versus weight of barium calibration curve (I) was made. Similarly, barium acetate, which served as the neutron flux monitor, was mixed with known weights of standard rocks, BCR-1 and G-2. Then a peak area (at 1.78 MeV due to28Al) versus weight of silicon (present in the standard rocks) calibration curve (II) was constructed which was corrected for flux variations. Flux corrections were made possible using curve (I). Utilizing curve (I) and curve (II) the percentage Si in granite samples obtained from Llano, Texas, was determined. This technique avoids any external neutron monitor or sample rotation system. The applicability of this approach may be limited to samples in which the internal flux monitor can be dispersed.
Abstract
KRIS offers the capability of resolving complex γ-spectra, even when spectra of the individual components are quite similar. A scheme is employed which allows for the use of half-lives as well as γ-ray energies in the least-squares resolution of γ-spectra. Options are also supplied for averaging of repetitive counts, least-squares smoothing of the data, iterative improvement of the weighting factors used in the least-squares solution, and use of either live or clock time counts. The number of control cards required for each sample has been minimized to simplify input. KRIS is written in FORTRAN IV and is being run under Fortran G and the Watfor compiler on the IBM 360/65.
Abstract
Capabilities of 14 MeV neutron activation analysis with a high output generator are evaluated and found to be comparable with conventional activation analysis regarding sensitivity and precision; additional elements are instrumentally accessible at trace levels. Nuclear reactions featuring higher selectivity are listed and their sensitivity is compared to the present state of 14 MeV activation. Quasi-promt activation (T<1 sec) expands the scope of the technique to rapid nondestructive assays of trace species in bulk samples.
Résumé
La mesure de traces d'éléments dans l'air ambiant a fait l'objet d'une attention accrue ces derniers mois, en raison d'un intérêt grandissant pour les dangers en puissance pour la santé, qui résultent de l'exposition prolongée à certaines substances toxiques. L'analyse par activation neutronique a été employée avec succès dans la recherche de traces d'éléments, et ce, pour un grand nombre d'études de l'environnement; elle semble convenir de façon idéale pour la détermination non-destructive multi-élémentaire de la composition de milieux de particules portées par l'air. Dans cet article, on rend compte des performances de l'analyse instrumentale par activation neutronique comme on le montre dans le cas de 40 échantillons d'air filtrées provenant d'une zone métropolitaine.
