Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

1 Publication
36Cl exposure dating with a 3-MV tandem
Steier, P.; Golser, R.; Kutschera, W.; Martschini, M.; Merchel, S.; Orlowski, T.; Priller, A.; Vockenhuber, C.; Wallner, A.;
36Cl AMS measurements at natural isotopic concentrations have yet been performed only at tandem accelerators with 5 MV terminal voltage or beyond. We have developed a method to detect 36Cl at natural terrestrial isotopic concentrations with a 3-MV system, operated above specifications at 3.5 MV.
An effective separation was obtained with an optimized split-anode ionization chamber design (adopted from the ETH/PSI Zurich AMS group), providing a suppression factor of up to 30.000 for the interfering isobar 36S. Despite the good separation, a relatively high sulfur output from the ion source (36S-/35Cl- = 5×10-11) resulted in a background corresponding to 36Cl/Cl = 3×10-14. The method was applied to samples containing between 105 and 106 atoms 36Cl/g rock from sites in Italy and Iran, which were already investigated by other laboratories for surface exposure dating. The 36Cl/Cl ratios in the range from 2×10-13 to 5×10-12 show a generally good agreement with the previous results.
These first measurements demonstrate that also 3-MV tandems, constituting the majority of dedicated AMS facilities, are capable of 36Cl exposure dating, which is presently the domain of larger facilities.
Keywords: 36Cl, AMS, isobar separation

Publ.-Id: 11922 - Permalink