THE PRODUCTION OF A HIGHLY POLARIZED ATOMIC CESIUM BEAM

We have produced a cesium beam of 10¹⁴ atoms s⁻¹ with more than 98% of the atoms in a single spin state. The beam was polarized by optically pumping it with a single laser diode whose frequency was switched between the 6s (F = 4)−6p_3/2(F = 5) and 6s(F = 3)−6p_3/2 (F = 4) transitions at 100 kHz. To do this, it was necessary to determine the frequency modulation characteristics of the laser. The same laser was used to simultaneously probe the atomic population distribution. We find this to be a remarkably simple and inexpensive way to produce a highly spin polarized beam.