  This communication describes the observation of a new type of dark
spontaneous-force optical trap (dark SPOT) obtained without the use of a mask
blocking the central part of the repumper laser beam. We observe that loading a
magneto-optical trap (MOT) from a continuous and intense flux of slowed atoms
and by appropriately tuning the frequency of the repumper laser is possible to
achieve basically the same effect of the dark SPOT, using a simpler apparatus.
This work characterizes the new system through measurements of absorption and
fluorescence imaging of the atomic cloud and presents a very simple model to
explain the main features of our observations. We believe that this new
approach may simplify the current experiments to produce quantum degenerated
gases.
