Isotopically selective atom counting using photon burst detection

Photon burst detection is used to count ${\mathrm{Mg}}^{+}$ ions in a 500-eV beam with high optical isotopic selectivity. Background rates of less than 1 count in 2 h have been achieved corresponding to an optical abundance sensitivity of 2×${10}^{\mathrm{-}8}$. © 1996 The American Physical Society.