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  • Author or Editor: E. Ricci x
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Abstract  

The kinetic energy of charged particles is rapidly degraded into large amounts of heat in the target; if biological samples are bombarded, chemical decomposition may result. A simple least-squares straight-line fitting procedure was applied to test the chemical stability of freeze-dried, compressed samples of human lung, brain andE. coli, under bombardment with a 0.33–0.48 μA beam of 0.7 MeV protons. The method showed no significant damage in these conditions, and also estimated the meximum length of ‘safe’ bombardment to be approximately 50 min. The samples were being subjected to proton-reaction analysis for ratios13C/12C and N/C when the least-squares test was performed; however, this method may be easily adapted to check- and roughly predict — sample stability in practically any activation, prompt-reaction, or related analysis based on charged-particle bombardment.

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We consider a class of integral transforms which generalize the classical Fourier Trans- form.We erive some theoretical error bounds for the corresponding approximate iscrete transforms,inclu ing the Discrete Fourier Transform.

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Résumé  

On a récemment installé un nouveau dispositif pour l'analyse par activation neutronique avec un flux thermique de 5X1014 cm−2 sec−1 au réacteur à haut flux du ORNL. Ce flux particulièrement élevé combiné avec un petit ordinateur et un programme adapté à la spectrométrie γ avec un détecteur Ge (Li), rend possible une irradiation plus courte, une analyse d'identification plus rapide et plus économique que si on utilise des moyens plus conventionnels. On discute des caractéristiques et des expériences du nouveau laboratoire d'analyse par activation neutronique à haut flux, de même des résultats obtenus sur plusieurs types de matrices concernent l'environnement pour le mercure, le cadmium, le brome, l'arsenic, le chlore et le sodium.

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Abstract  

The forensic activation analyst must often evaluate his own results as they relate to certain legal or moral situations, since investigative officers, and courts of law are not usually competent to make judgements of the validity or meaning of scientific data. In providing scientific evidence in court, two criteria for criminal identification must be met: (1) suspect's sample should be similar to sample found at the scene of the crime, (2) samples relared to other people in the same statistical population should not generally match that found at the crime site. When two or more specimens are submitted for comparison by NAA they will usually fall into one of three classes: (a) materials about which we have partial or inconclusive data, (c) materials with an excellent analytical data background. Ideally all cases would fall in category c; in practice, very few. Some examples of cases and/or situations that fall into these three categories in both individual and corporate investigations are given.

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