Construction of an atomic funnel for a slow, high density atomic beam

The deceleration and cooling of as large a fraction as possible of the atoms from a thermal beam without serious loss of density has been addressed. By combining a number of techniques known from laser cooling and trapping of atoms a beam of Na atoms with a density exceeding that of a thermal beam and a tunable velocity of 1-5 m/s has been produced. The temperature of the beam was measured to be approximately 170 μK, corresponding to an rms velocity spread of <45 cm/s. The basic idea of the design is an extended 2-D magnetooptic trap with a drift velocity along the axis. Atoms originating from a thermal source and slowed by a frequency chirped laser beam are continuously guided by this trap into a region of optical molasses. Slight imbalances in the intensity of the molasses beams provide a very accurate control of the direction of the slow atomic beam.