  We have realized a high-resolution time-of-flight mass spectrometer combined
with a magneto-optical trap. The spectrometer enables excellent optical access
to the trapped atomic cloud using specifically devised acceleration and
deflection electrodes. The ions are extracted along a laser beam axis and
deflected onto an off axis detector. The setup is applied to detect atoms and
molecules photoassociated from ultracold atoms. The detection is based on
resonance-enhanced multi-photon ionization. Mass resolution up to m/Delta m_rms
= 1000 at the mass of 133Cs is achieved. The performance of this spectrometer
is demonstrated in the detection of photoassociated ultracold 7Li133Cs
molecules near a large signal of 133Cs ions.
