IMPROVING THE DESIGN OF A WATER-COOLED ATOM TRAP TO INCREASE SENSITIVITY AND PRECISION

An improvement to the design of the dual-tube water-cooled atom trap i s 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 b e exposed to the light beam compared with the earlier flat design whic h had an arm of the tube passing through the light beam. A sturdier da mping system is shown which prevented the tubes from bouncing in the b eam after collection of the metal and during measurement. Parameters s uch as the cooling water pressure through the tubes were optimized, as well as the positioning of the tubes with respect to the flame and th e 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 alignmen t. 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 sens itivity 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 incr ease in sensitivity will be seen with other elements previously examin ed.