Fig. 1.

Typical phase images of the reduced cyclotron motion for ${}^{129}$Sb${}^{+}$ ions obtained with the PI-ICR technique. The color mixture of each point represents the probabilities of belonging to the excited state (red), the ground state (green), and the background (blue). The determined number of nuclei in each component from the phase image is estimated by the BGM model. In the upper panel the phase-accumulation time is set to 24 ms, while in the lower panel it is 39 ms. Contour lines illustrate the normal distributions of the components of the BGM model