A continuous, low-velocity, nearly monochromatic atomic beam is created using
laser cooling and two-dimensional magneto-optic trapping. Rubidium atoms from an
effusive oven are slowed and cooled using Zeeman-tuned slowing. The scattering force
from a counter-propagating, frequency-stabilized diode laser beam is used to decelerate
the thermal beam of atoms to a velocity of ~ 20 m/s. A spatially varying magnetic field is
used to Zeeman shift the resonance frequency of the atom to compensate for the changing
Doppler shift, thereby keeping the slowing atoms resonant with the fixed frequency laser.
This slowing process also cools the beam of atoms to a temperature of a few Kelvin. The
slow beam of atoms is loaded into a two-dimensional magneto-optic trap or atomic
funnel. The atoms are trapped along the axis of the funnel and experience a molassestype
damping force in all three spatial dimensions. By frequency shifting the laser beams
used to make the trap, the atoms are ejected at a controllable velocity. The continuous
matter-wave source has a controllable beam velocity in the range of 2 to 15 m/s,
longitudinal and transverse temperatures of approximately 500 ��K, and a flux of
3.4 x10��� atoms/s. At 10 m/s, the de Broglie wavelength of the beam is 0.5 nm. The
spatial profile of the atomic beam was characterized 30 cm from the exit of the atomic
funnel using a surface ionization detector. The low-velocity atomic beam is an ideal
source for atom interferometry and a variety of applications in the field of atom optics. / Graduation date: 1997
|22 January 1997
|Mayer, Shannon K.
|McIntyre, David H.
|Oregon State University
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