Improving the design of a water-cooled atom trap to increase sensitivity and precision

Abstract

An improvement to the design of the dual-tube water-cooled atom trap is discussed. The shape of the tubes was altered from the flat type to what is described as a ‘bent’ tube. This enabled more of the tube to be exposed to the light beam compared with the earlier flat design which had an arm of the tube passing through the light beam. A sturdier clamping system is shown which prevented the tubes from bouncing in the beam after collection of the metal and during measurement. Parameters such as the cooling water pressure through the tubes were optimized, as well as the positioning of the tubes with respect to the flame and the light beam (horizontal alignment, or front to back movement parallel to the burner slot). The latter was found to be critical for optimum sensitivity. Figures are presented which show splitting of the signal on the recorder trace resulting from the effects of incorrect alignment. Sensitivities for the improved design were found to be 0.3579 and 2.994 ng ml^–1 for cadmium and lead, respectively, an increase in sensitivity over the earlier design, which was 0.8813 and 3.544 ng ml^–1, respectively, for cadmium and lead. It is believed that the same increase in sensitivity will be seen with other elements previously examined.