Collon, P.

Paper	Title	Page
MOCO-C05	Development of ECR high purity liners for reducing K contamination for AMS studies of 39Ar	48
	C. J. Schmitt, M. Bowers, P. Collon, D. Robertson University of Notre Dame, Notre Dame F. Calaprice, C. Galbiati PU, Princeton, New Jersey D. Henderson, C. L. Jiang, R. C. Pardo, E. Rehm, R. H. Scott, R. C. Vondrasek ANL, Argonne, Illinois W. Kutschera VERA, Wien M. Paul The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem
	The first application of 39Ar AMS at the ATLAS linac of Argonne National Laboratory (ANL) to date ocean water samples relevant to oceanographic studies using the gas-filled magnet technique to separate the 39K-39Ar isobars was most successful and has been reported on. In particular the use of a quartz liner in the plasma chamber of the Electron Cyclotron Resonance (ECR) ion source enabled a 39K reduction of a factor ~100 compared to previous runs without liners and allowed for our current lowest detection limit of 39Ar/Ar = 4.2x10-17. We are currently working on improving the AMS method for 39Ar by following two development paths to allow for higher beam currents while lowering 39K rates. The first option is to modify the design of the quartz liner to provide active water cooling. The second option is to evaporate high purity aluminum directly on the surface of the water-cooled ion source chamber. The overall driving force for AMS is to search for a source of argon that has a low concentration of 39Ar. Such a source of argon would be useful for new liquid argon detectors that are being developed for detecting dark matter WIMPs (Weakly Interacting Massive Particles).
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