  We study the regular or chaotic character of orbits in a 3D dynamical model,
describing a triaxial galaxy surrounded by a spherical dark halo component. Our
numerical experiments suggest that the percentage of chaotic orbits decreases
exponentially as the mass of the dark halo increases. A linear increase of the
percentage of the chaotic orbits was observed as the scale length of the halo
component increases. In order to distinguish between regular and chaotic
motion, we chose to use the total angular momentum Ltot of the 3D orbits as a
new indicator. Comparison with other, previously used, dynamical indicators,
such as the Lyapunov Characteristic Exponent or the P(f) spectral method, shows
that the Ltot indicator gives very fast and reliable results for characterizing
the nature of orbits in galactic dynamical models.
