  We report a measurement of the lifetime of the cesium $7s\,^2S_{1/2}$ state
using time-correlated single-photon counting spectroscopy in a vapor cell. We
excite the atoms using a Doppler-free two-photon transition from the
$6s\,^2S_{1/2}$ ground state, and detect the 1.47$\mu$m photons from the
spontaneous decay of the $7s\,^2S_{1/2}$ to the $6p\,^2P_{3/2}$ state. We use a
gated single photon detector in an asynchronous mode, allowing us to capture
the fluorescence profile for a window much larger than the detector gate
length. Analysis of the exponential decay of the photon count yields a
$7s\,^2S_{1/2}$ lifetime of 48.28$\pm$0.07ns, an uncertainty of 0.14%. These
measurements provide sensitive tests of theoretical models of the Cs atom,
which play a central role in parity violation measurements.
