Lifetime of the 7s6d ^{1}D_{2} atomic state of radium

The lifetime of the 7s6d D-1(2) state of atomic radium is determined to be 385(45) mu s using cold Ra-226 atoms prepared in a magneto-optical trap. The D-1(2) state is populated from the decay of the P-1(1) state which is excited by a pulse of 483 nm light. The decay of the D-1(2) state is observed by detecting delayed fluorescence at 714 nm from the last step in the decay sequence P-1(1)-D-1(2)-P-3(1)-S-1(0). The measured lifetime is compared to a number of theoretical calculations. An improved value of the 7s7p P-1(1) level of 20 715.598(6) cm(-1) is obtained.