We describe an experiment which demonstrates the feasibility of trappi
ng significant quantities of short-lived radioactive atoms with laser
light. A thermal beam of 22.5 sec half-life Na-21 atoms was produced o
n-line at the LBL 88'' Cyclotron. After decelerating the beam using a
Zeeman-tuned slowing technique we stored about 4 x 10(3) Na-21 atoms i
n a magneto-optical trap. The number of trapped atoms is large enough
to be used in experimental studies of the beta decay of Na-21. The bas
ic method can be adapted for other rare isotopes.