Berlin 2001 – scientific programme

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AMPD: EPS AMPD

AMPD 6: Sitzung 6

AMPD 6.8: Talk

Wednesday, April 4, 2001, 15:00–15:25, H104

Ultrasensitive Trace–Isotope Analysis with a Magneto–Optical Trap — •Z.-T. Lu¹, K. Bailey¹, X. Du², Y.M. Li¹, T.P. O’Connor¹, and L. Young³ — ¹Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA — ²Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA — ³Chemistry Division, Argonne National Laboratory, Argonne, IL 60439, USA

We have developed a new method of ultrasensitive trace–isotope analysis based upon the technique of laser manipulation of neutral atoms [C.Y. Chen et. al., Science 286, 1139 (1999)]. This new method allows us to count individual ⁸⁵Kr and ⁸¹Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10⁻¹¹ and 10⁻¹³, respectively. Isotope analysis of ⁸¹Kr can be used to date polar ice; and ⁸⁵Kr is a tracer used in monitoring nuclear wastes. In this experiment metastable Kr atoms were produced in a discharge, decelerated via the Zeeman slowing technique, and captured by a magneto–optical trap where the atoms were counted by measuring their fuorescence. At present our system is capable of counting, in average, one ⁸¹Kr atom for about 12 minutes with a total effciency of 2 × 10⁻⁷. We are currently working to improve our system effciency by re-circulating the gas in the vacuum system. This method can be used to analyze many other isotope tracers for a wide range of applications.