Laser Trapping of ²²⁵Ra and ²²⁶Ra with Repumping by Room-Temperature Blackbody Radiation

We have demonstrated Zeeman slowing and capture of neutral ²²⁵Ra and ²²⁶Ra atoms in a magneto-optical trap. The intercombination transition ¹S₀→³P₁ is the only quasicycling transition in radium and was used for laser-cooling and trapping. Repumping along the ³D₁→¹P₁ transition extended the lifetime of the trap from milliseconds to seconds. Room-temperature blackbody radiation was demonstrated to provide repumping from the metastable ³P₀ level. We measured the isotope shift and hyperfine splittings on the ³D₁→¹P₁ transition with the laser-cooled atoms, and set a limit on the lifetime of the ³D₁ level based on the measured blackbody repumping rate. Laser-cooled and trapped radium is an attractive system for studying fundamental symmetries.