A gas handling technique has been developed for dosing CO2 into a gas ion source of the Erlangen AMS facility [1]. Further investigations and developments have resulted in a system that enables the measurement of gaseous samples with carbon masses down to 1µg [2]. The system has primarily been designed for the coupling of an elemental analyzer with a gas ion source. Moreover, the system can be connected to any other system that offers CO2, e.g. gas ampoules, gas chromatograph, etc. The principle of the technique is to store and isolate CO2 cryogenically. The CO2 can be fed into the ion source via a glass capillary, connected to the CO2 reservoir. By regulating the CO2 pressure the CO2 flow into the ion source is adjusted. The outstanding advantage of this easy technique is the possibility of its complete automation. For the use of the system with an elemental analyzer we created application software that controls the combustion of the sample, the cryogenic storage and the exact dosage of the CO2 into the ion source. Besides the application of using CO2 for radiocarbon dating our gas handling system opens new possibilities of research in fields where only small samples are available or large series of samples have to be measured quickly, e.g. environmental or biomedical research. In this contribution a closer view on the technique, the software and the functionality of the gas handling system will be given. Finally measurement results of reference standards in the range of 1µg to 300µg will be shown.
[1] T. Uhl, W. Kretschmer, W.Luppold, A. Scharf, Direct coupling of an elemental analyzer and a hybrid ion source for ams measurements. Radiocarbon 46(1):65-75
[2] T. Uhl, W. Kretschmer, W.Luppold, A. Scharf, AMS measurements from microgram to milligram. To be published in Nucl. Instr. and Meth. B 2005
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