  The problem for molecular identification knows many solutions which include
mass spectrometers whose mass sensitivity depends on the performance of the
detector involved. The purpose of this article is to show by means of molecular
dynamics simulations, how a laser-cooled ion cloud, confined in a linear
radio-frequency trap, can reach the ultimate sensitivity providing the
detection of individual charged heavy molecular ions. In our simulations, we
model the laser-cooled Ca + ions as two-level atoms, confined thanks to a set
of constant and time oscillating electrical fields. A singly-charged molecular
ion with a mass of 10 6 amu is propelled through the ion cloud. The induced
change in the fluorescence rate of the lather is used as the detection signal.
We show that this signal is due to a significant temperature variation
triggered by the Coulombian repulsion and amplified by the radio-frequency
heating induced by the trap itself. We identify the optimum initial energy for
the molecular ion to be detected and furthermore, we characterize the
performance of the detector for a large range of confinement voltages.
