Collisional excitation and destruction of metastable states in a stored ion beam

A laser probing technique has been applied to a stored ion beam of ${\mathrm{Xe}}^{+}$ to study collisional destruction of metastable states as well as collisional excitation by the residual gas in the storage ring. The results are of great importance for the evaluation of lifetime measurements of metastable states in storage rings. For the states studied in ${\mathrm{Xe}}^{+},$ it was found that neither of the two processes caused systematic errors in the lifetime determination. It is also shown that the method can yield partial cross sections for collisional excitation.