  We offer interferometry models for thermal ensembles with one-body losses and
the phenomenological inclusion of perturbations covering most of the thermal
atom experiments. A possible extension to the many-body case is briefly
discussed. The Ramsey pulses are assumed to have variable durations and the
detuning during the pulses is distinguished from the detuning during evolution.
Consequently, the pulses are not restricted to resonant operation and give more
flexibility to optimize the interferometer to particular experimental
conditions. On this basis another model is devised in which the contrast loss
due to the unequal one-body population decays is cancelled by the application
of a non-standard splitting pulse. For the importance of its practical
implications, an analogous spin-echo model is also provided. The developed
models are suitable for the analysis of atomic clocks and a broad range of
sensing applications, they are particularly useful for trapped-atom
interferometers.
