  The lifetime of an atom trap is often limited by the presence of residual
background gases in the vacuum chamber. This leads to the lifetime being
inversely proportional to the pressure. Here we use this dependence to estimate
the pressure and to obtain pressure rate-of-rise curves, which are commonly
used in vacuum science to evaluate the performance of a system. We observe
different rates of pressure increase in response to different levels of
outgassing in our system. Therefore we suggest that this is a sensitive method
which will be useful in applications of cold atom systems, in particular where
the inclusion of a standard vacuum gauge is impractical.
