Experiments with Supersonic Beams as a Source of Cold Atoms

MCP signal [arbitraty units]
3.0
2.0
1.0
0.0
(a)
(b)
3 4 5
Time of flight [ms]
(c)
(d)
(e)
MCP signal [arbitrary units]
0.3
0.2
0.1
0.0
(a)
(f)
(g)
(h)
3 4 5 6
Time of flight [ms]
Figure 4.30: Metastable neon slowing data from the 64 stage coilgun. Each time of
flight curve is the average of 20 individual measurements. The slowed curves only
show the slowed portion of the beam for clarity. The time of flight signal for a beam
without firing the coils is shown in (a). The velocities of the beams are (a) 446.5m/s,
(b) 222 m/s, (c) 184.7 m/s, (d) 142.7 m/s, (e) 109.9 m/s, (f) 84.1 m/s, (g) 70.3m/s,
and (h) 55.8 m/s. These results are summarized in table 4.2.
4.5.4 64 Stage Data and Results
Results of using the coilgun to slow metastable neon are now presented. The
MCP is used to record time-of-flight signals for a given coil timing configuration. The
timing configuration is used to record two sets of data, one with the MCP in the
retracted position, and one with the MCP in the extended position. In this manner,
the velocity can be measured by observing the time it takes the slowed beam to
propagate the extra distance to the MCP. Similarly, the temperature of the beam can
be measured by observing how much the beam spreads in this time.
Time-of-flight measurements of the beam are presented in figure 4.30. The
initial beam without firing the coils is shown in curve (a), and this beam has a
velocity of 446.5 ± 2.5 m/s and a temperature of 525 ± 10 mK. This beam is slowed in
the coilgun using phases between 36 ◦ and 44 ◦ , where the phase used is held constant
for each coil in the coilgun (constant phase for the entire slowing sequence). The
slowed beams have velocities between 222 ± 11 m/s on the high side, and as slow as
105