Poster f

1
Magneto-Optical Trapping of Stark-Slowed
Metastable Helium Atoms
goal - study of ionisation dynamics of
metastable helium atoms in a trap - cold
collisions of ultraslow He - storage of
metastable helium atoms in an electro-dynamical
trap - realization of a storage-ring for slow
helium atoms
vstart 1000 m/s
characteristics of the used diode lasers for
transversal cooling and trapping
For stabilizing the diode lasers we use the mean
of saturation spectroscopy. We extract the
control signal out of the spectrum of the
-transition. The laser linewidth of the
diode lasers is determined to about 5 MHz by
measuring the beat signal on a fast photodetector.
spectrum
beat signal
transversal cooling and deflection of the He
beam
To separate the metastable helium atoms from the
ground-state atoms, the He source is placed
off-axis, so that only the metastables will be
deflected into the Stark-slower-section by the
use of the diode laser at l 1083 nm.
outlook
trapping and guiding He atoms by means of
dynamical electric fields
electrodes
calculated trajectory
U3
U1
Our aim is to construct a trap or an atom-guide
for helium atoms based on rotating electric
fields. Simulations show the possibility to hold
helium atoms with v lt 2 m/s against gravity. With
variable structures of the rods it will be
possible to get a storage-ring for metastable
helium atoms, where we can study ultracold
collisions of He.
U4
U2
Getting a closed trajectory of a trapped atom, we
used following parameters trap
dimensions distance of the rods 8 mm radius
of the rods 2 mm applied voltage U 20,0
kV frequency of the applied voltage n 3000 Hz