Hannover 2003 – wissenschaftliches Programm

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MS: Massenspektrometrie

MS III: HV III

MS III.1: Hauptvortrag

Montag, 24. März 2003, 12:00–12:30, F 428

The AlCaTraz experiment: Towards ultra-sensitive isotope analysis of calcium — •Ronnie Hoekstra, Steven Hoekstra, and Reinhard Morgenstern — KVI, Atomic Physics, RijksUniversiteit Groningen, Zernikelaan 25, 9747 AA Groningen, the Netherlands

We are developing a new apparatus for ultra-sensitive trace isotope analysis of calcium isotopes. Using modern optical methods, specific isotopes of calcium will be selectively cooled, trapped and detected in a Magneto-Optical Trap (MOT). Of special interest is the radioactive isotope ⁴¹Ca, which might be used for dating calcium-containing material from the pleistocene (the half-life of ⁴¹Ca is 105,000 year) and as a biomedical tracer for the osteoporosis studies. The main experimental challenge is the very low natural abundance of ⁴¹Ca relative to ⁴⁰Ca, which is only 10⁻¹⁵ to 10⁻¹⁴. Until now this kind of experiments have only been attempted with Accelerator Mass Spectrometry and more recently Resonant Ionization Mass Spectrometry. In our AlCaTraz experiment, Ca is evaporated from an oven, after which the atoms are decelerated in a Zeeman slower. Before and after the Zeeman slower, optical molasses is used to collimate the atom beam, and after the Zeeman slower also to deflect the desired isotope. These atoms are then captured in a standard MOT, and detected by their fluorescence. We performed Monte Carlo type simulations of the different stages, collimation, slowing down, deflection and trapping. In addition to the simulations, the experimental status will be discussed and as far as possible comparison will be made with the simulations.