Target preparation for milligram sized 14C samples and data evaluation for AMS measurements

Andree, Michael; Beer, Jürg; Oeschger, Hans; Bonani, G.; Hofmann, H.J.; Morenzoni, E.; Nessi, M.; Suter, M.; Wölfli, W. (1984). Target preparation for milligram sized 14C samples and data evaluation for AMS measurements. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 5(2), pp. 274-279. Elsevier 10.1016/0168-583X(84)90526-3

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Our preparation technique produces in a glow-discharge an amorphous carbon deposit on a copper substrate. The process starts with 1.6 cm3 CO2 STP (900 μg carbon) which is reduced over hot zinc to CO and subsequently cracked in the discharge. The yield of the process is typically 80%. With these targets in the Zürich ion source ion currents up to 20 μA are obtained. The background of samples prepared with this technique is presently around 30 ka (2.5% MODERN). The precision after half an hour measuring time for a modern sample is 0.7% and 2.7% for a three half-lives old sample, including the errors of the background and the NBS oxalic acid measurement. The method we use to correct for the background of the preparation and the accelerator as well as for the fractionation in the accelerator is presented.

Item Type:	Journal Article (Original Article)
Division/Institute:	08 Faculty of Science > Physics Institute > Climate and Environmental Physics
Subjects:	500 Science > 530 Physics
ISSN:	0168-583X
Publisher:	Elsevier
Language:	English
Submitter:	BORIS Import 2
Date Deposited:	16 Sep 2021 15:11
Last Modified:	16 Sep 2021 15:11
Publisher DOI:	10.1016/0168-583X(84)90526-3
URI:	https://boris.unibe.ch/id/eprint/158473