Lifetime of the $1s2s{}^{3}S_1$ metastable level in $\mathrm{He}$-like ${\mathrm{S}}^{14+}$ measured with an electron beam ion trap

A precision measurement of the lifetime of the lowest excited level of the $\mathrm{He}$-like ${\mathrm{S}}^{14+}$ ion carried out at the Livermore EBIT-II electron beam ion trap yielded a value of $(703\pm 4)\mathrm{ns}$. Our method extends the range of lifetime measurements accessible with electron beam ion traps into the nanosecond region and improves the accuracy of currently available data for this level by an order of magnitude.

Figure 1

Top: exponential decay fit to the He-Like ${\mathrm{S}}^{16+}$ ion data obtained with a proportional counter. Bottom: residuals of the decay fit.

Figure 2

Fractional difference of experimental measurements of the lifetime of the $1s2s{}^{3}S_1$ level in various He-like ions and calculated values from Johnson, Plante, and Sapirstein [39], defined as $({\tau }_{\mathrm{theor}}-{\tau }_{\mathrm{expt}})∕{\tau }_{\mathrm{theor}}$.