High Intence Low Velocity Atomic Beam
Cold atomic beams characterized by a small averagevelocity of atoms at a high intensity and high phase spacedensity are widely used in various experiments in atomic beam optics, interferometry, and lithography. Low-energy atomic beams can be obtained by method of laser cooling, which is known in several variants employing the Zeeman effect, frequency-chirped laser radiation, isotropic light, and wideband laser radiation. Unfortunately, the process of cooling by all these techniques is accompanied by unavoidable increase in the transverse temperature of atoms and, hence, by a decrease in the beam brightness and phase space density.
We have developed a new method for obtaining cold atomic beams of high intensity (7.2x 1012 s-1) and a small average velocity of atoms (12 m/s) and have studied this method in application to a beam of 85Rb atoms (Fig.1). The proposed technique employs the Zeeman laser cooling of thermal 85Rb atoms in transverse magnetic field. Application of the transverse magnetic field allowed us to obtain the optimum distribution of magnetic field along the beam axis, which is necessary for effective cooling. Using the scheme with transverse magnetic field, we succeeded in creating a compact and effective Zeeman slower ensuring the formation of intense beams of atoms with an average velocity as low as 10 m/s [1].
Fig.1 The velocity distribution of 85Rb atoms in a beam upon Zeeman slowing for various detunings of the cooling laser frequency Δ(MHz): (a) –39, (b) –46, (c) –54, (d) –66, (e) –77.
Fig.2 The Zeeman slower general view.
Fig.3 The flux and average velocity of cooled atoms obtained in our study in comparison to the results obtained by other researchers using cooled atomic beams (circle) and atomic beams from 3D-MOT (square):
