Laser cooling and trapping of sodium atoms in the F=1 ground state

We have developed a new scheme to produce a dense trap of sodium atoms in the magneto-optical trap using the transition of F=1 to F'=0 states. In a conventional Zeeman slower a bias magnetic field is applied in the deceleration region to prevent the optical pumping to the F=1 state, so that sodium atoms interact with the cooling radiation of F=2 to F'=3. As a result, many of slow atoms in the F=2 state continue to decelerate adiabatically even at the exit of the solenoid and remain inside the magnetic field. However, slow atoms could be extracted outside the magnetic field, if they are transferred to the F=1 state by the optical pumping via the F'=2 state. Therefore, we reduced the strength of the bias magnetic field. We trapped the slow sodium atoms in the F=1 state directly in the magneto-optical trap.