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Updated: Aug 22, 2026

Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
First measurement of the velocity of slow antihydrogen atoms
G Gabrielse1, A Speck, C H Storry
1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA. gabrielse@physics.harvard.edu
Abstract:
The speed of antihydrogen atoms is deduced from the fraction that passes through an oscillating electric field without ionizing. The weakly bound atoms used for this first demonstration travel about 20 times more rapidly than the average thermal speed of the antiprotons from which they form, if these are in thermal equilibrium with their 4.2 K container. The method should be applicable to much more deeply bound states, which may well be moving more slowly, and should aid the quest to lower the speed of the atoms as required if they are to be trapped for precise spectroscopy.
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