Reducing potassium contamination for AMS detection of 39Ar with an electron-cyclotron-resonance ion source

Author(s)

Philippe Collon, Matthew Bowers, F. Calaprice, C. Galbiati, D. Henderson, T. Hohman, Chun Ling Jiang, Walter Kutschera, H. Y. Lee, B. Loer, R. C. Pardo, M. Paul, E. Rehm, D. Robertson, C. Schmitt, R. Scott, R. Vondrasek

Abstract

The first application of ³⁹Ar Accelerator Mass Spectrometry

(AMS) at the ATLAS facility of Argonne National Laboratory was to date

ocean water samples relevant to oceanographic studies using the

gas-filled magnet technique to separate the ³⁹K–³⁹Ar

isobars. In particular the use of a quartz liner in the plasma chamber

of the electron cyclotron resonance ion source enabled a ³⁹K reduction of a factor ∼130 compared to previous runs without liners, and allowed us to reach a detection sensitivity of ³⁹Ar/Ar = 4 × 10⁻¹⁷.

In order to improve this sensitivity and allow the measurement of lower

ratios, higher ion source currents and a lower overall ³⁹K

background are necessary. This paper summarizes our efforts to

investigate new methods combining low level potassium cleaning

techniques with the use of ultra-pure aluminum liners in the plasma

chamber of the ion source. The aim of the study was to improve by 1–2

orders of magnitude the ³⁹Ar detection sensitivity required

in the selection of ultra-pure materials for detectors used in weakly

interacting massive particle dark matter searches.

Organisation(s)

Isotope Physics

External organisation(s)

University of Notre Dame, Princeton University, Argonne National Laboratory, Hebrew University Jerusalem

Journal

Nuclear Instruments & Methods in Physics Research. Section B. Beam Interactions with Materials and Atoms

Volume

283

Pages

77-83

No. of pages

7

ISSN

0168-583X

DOI

https://doi.org/10.1016/j.nimb.2012.04.020

Publication date

2012

Peer reviewed

Yes

Austrian Fields of Science 2012

1030 Physics, Astronomy

Portal url

https://ucrisportal.univie.ac.at/en/publications/2ace9684-2438-48c6-950b-c47f0359ad14