Gamma-ray analysis of light elements

To verify this hypothesis, low volume samplers have been operated in parallel with the air pollution control district s Km samplers. The samples collected were analyzed optically for elemental carbon and by the Gamma Ray Analysis of Light Elements (GRALE) technique for total carbon. These data were used to assess the concentration of elemental and total carbon aerosols present during the winter months in Los Angeles. It was established that the Km samplers can be calibrated to read elemental carbon concentrations. This calibration can be used to reconstruct historical elemental carbon levels at seven sites in Los Angeles. 

Aerosol carbon concentrations have been measured at two sites in the Los Angeles basin. Samples were analyzed for total carbon content and for elemental carbon content by the Gamma Ray Analysis of Light Elements technique and by several optical methods. Elemental carbon was shown to constitute a substantial fraction of total carbonaceous aerosol mass in the wintertime in Los Angeles. 

R.B. Bouiton, G.T. Ewan, Simultaneous analysis of light elements using prompt nuclear reaction gamma rays, Anal. Chem. 49 (1977) 1297-1303. 

Prompt activation analysis (Erdtmann and Petri, 1986 Alfassi, 1990) uses the prompt radiation accompanying a nuclear reaction for determining elemental or isotopic concentrations. The variety of prompt methods is large because a sample can be irradiated with various particles - neutrons, charged particles or gamma-rays. Prompt activation analysis permits the determination of several elements - about 17 elements in environmental matrices (Germani et al., 1980) - but most analysis are used for the determination of light elements (H, He, Li, B, C, N, Si, S, Cl) as well of Cd and Gd. 

Activation analysis methodology is quite similar to other instrumental analysis methods that use energy sources of either light, heat, X rays, or electricity to irradiate a material to bring about the emission of characteristic radiations. The detection and measurement of these radiations can then be used to indicate the amount of an elemental species in the material. Activation analysis requires a source of nuclear particles, such as neutrons, charged particles, or gamma rays, to bombard (or irradiate) the sample material to make it radioactive. 

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