Publikationen

Recent advances in AMS of 36Cl with a 3-MV-tandem

Autor(en)
Martin Martschini, Oliver Forstner, Robin Golser, Walter Kutschera, Stefan Pavetich, Alfred Priller, Peter Steier, Martin Suter, Anton Wallner
Abstrakt

Accelerator mass spectrometry (AMS) of (36)Cl (t(1/2) = 0.30 Ma) at natural isotopic concentrations requires high particle energies for the separation from the stable isobar (36)S and was so far the exclusive domain of tandem accelerators with at least 5 MV terminal voltage. Using terminal foil stripping and a detection setup consisting of a split-anode ionization chamber and an additional energy signal from a silicon strip detector, a (36)S suppression of >10(4) at 3 MV terminal voltage was achieved. To further increase the (36)S suppression energy loss straggling in various counter gases (C(4)H(10), Ar-CH(4) and C(4)H(10)-Ar) and the effect of "energy focusing" below the maximum of the Bragg curve was investigated. The comparison of experimental data with simulations and published data yielded interesting insights into the physics underlying the detectors. Energy loss, energy straggling and angular scattering determine the (36)S suppression. In addition, we improved ion source conditions, target backing materials and the cathode design with respect to sulfur output and cross contamination. These changes allow higher currents during measurement ((35)Cl(-) current approximate to 5 mu A) and also increased the reproducibility. An injector to detector efficiency for (36)Cl ions of 8% (16% stripping yield for the 7+ charge state in the accelerator, 50% (36)Cl detection efficiency) was achieved, which can favorably be compared to other facilities. The memory effect in our ion source was also thoroughly investigated. Currently our measured blank value is (36)Cl/Cl approximate to 3 x 10(-15) when samples with a ratio of 10(-11) are used in the same sample wheel and (36)Cl/Cl approximate to 5 x 10(-16) if measured together with samples with a ratio of 10(-12) or below. This is in good agreement with the lowest so far published isotope ratios around 5 x 10(-16) and demonstrates that 3 MV tandems can achieve the same sensitivity for 360 as larger machines

Organisation(en)
Isotopenphysik
Externe Organisation(en)
Eidgenössische Technische Hochschule Zürich
Journal
Nuclear Instruments & Methods in Physics Research. Section B. Beam Interactions with Materials and Atoms
Band
269
Seiten
3188-3191
Anzahl der Seiten
4
ISSN
0168-583X
DOI
https://doi.org/10.1016/j.nimb.2011.04.016
Publikationsdatum
2011
Peer-reviewed
Ja
ÖFOS 2012
103013 Ionenphysik
Link zum Portal
https://ucris.univie.ac.at/portal/de/publications/recent-advances-in-ams-of-36cl-with-a-3mvtandem(7062aace-d73a-4ba8-983d-3153dbc6e2a6).html