(a) 3D view of the vacuum system. HV region on the left side contains the atomic source and the optical access for the pre-cooling stage. The differential pumping channel connects this to the UHV region where the experiment is performed in a clean environment. Light beams (yellow) and magnets (red-blue) are shown. (b) Magnification of the compact slowing/cooling region. (c) 2D view of the pre-cooling plane showing atomic sources and beams configuration.
Sketch of the optical setup used for producing all the light beams needed to cool sodium atoms. Reported power values indicate the power output of the devices, without considering further power losses. Signed numbers in the blue boxes report the chosen order (±1) of the acousto-optic modulator (AOM) and its driving frequency in MHz.
Representation of the field generated by the magnets in the 2D MOT central vertical plane (y = 0) orthogonal to the chamber axis. The color scale is a function of the magnitude of the field, while the vectors represent its direction. The four magnet stacks are located in (x, y, z)=(0, ±37, ±49) mm, the two on top being oriented along −x and oppositely the other two. The plot on the left shows magnetic field and gradient along the central (x = y = 0) vertical axis of the 2D MOT, along which the ZS acts. The field along y axis is zero.
(a) Measured flux of atoms (green circles) captured in the 3D MOT as a function of the frequency detuning of the 2D MOT beams. Central data are fit to a Gaussian (black line) to find the best frequency. (b) Best ZS frequency (red) and maximum flux recorded (yellow) for different ZS intensities. The inset shows a typical dependence of atomic flux on the ZS frequency at fixed intensity. (c) Comparison between the vapor pressure of sodium (blue line) and the 3D MOT loading rate (red circles) as a function of the oven temperature. For this data set (c) the repumping power in the 2D MOT and ZS was about 8 times smaller than the standard one given in Table I . This explains why the maximum flux in (c) is significantly smaller than in (a) and (b).
Measured time of flight distribution of the atomic beam (left). Velocity distribution (right) of the atomic beam deduced from the time of flight and the known distance between the MOTs.
Flux distribution ϕ(v) of atoms emitted by the oven with (red) and without (blue) the ZS effect for a sample at 210 °C. Inset: ZS output velocity, v 1, as a function of the starting velocity at the oven, v 0. A large velocity class is slowed down to 19 m/s, below the 2D MOT capture velocity v c.
Set of frequency detuning (from the |F = 2⟩ → |F′ = 3⟩ transition) and intensity for each beam in the atomic source.
Atomic source performances.
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