Experiments to Control Atom Number and Phase-Space Density in ...

not trapped by the MOT impinge on this viewport. It is therefore constantly heated to a
temperatue of about 120 ◦ C with a band heater to avoid coating of the window. Both the
6 inch custom nipple and the 6 inch elbow are electropolished (Central Electropolishing
Co.) to reduce outgassing in the science chamber.
7.1.4 Bake-Out
Ti:Sub pump
ion gauge
Zeeman slower window
angle valve
ion pump
Figure 7.10: Science chamber assembly.
To achieve vacuum pressures in the 10 −10 Torr range or better, ion pumps and
titanium sublimation pumps, rather than turbo-pumps, are connected to the vacuum
system. This also eliminates moving pumps, reducing vibrations. However, for the initial
pump-out a turbo pump is necessary. The turbo-pump is connected to the vacuum
chamber through two angle valves. After bake-out these valves are closed, and the
turbo-pump can be disconnected.
Ultra-high vacuum pressures would be difficult to reach without baking of the
chamber. Baking increases the outgassing speed, especially for water attached to the
stainless steel walls of the vacuum chamber parts, thus drastically decreasing the amount
of time necessary to reach the desired pressure. At pressures of 10 −6 Torr or better the
baking of the chamber can start. Typically the chamber is wrapped with heater-tapes
and insulated using aluminum foil. The higher the temperature during the bake-out,
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