Investigation of the process of radiation capture in an atomic beam

V. A. Grinchuk, I. A. Grishina, E. F. Kuzin +3 more

In this paper we present some new results concerning the observed anomalous frequency properties of the process of the neutral atom scattering in the standing light wave field near the reflecting mirror. The investigations were carried out using the method of scattering of the sodium atomic strip beam, intersecting at right angle the region of the standing light wave field. The standing light wave field was formed by two counterpropagating waves of resonant laser radiation -- incident and reflected from the mirror, mounted at a distance of about 1 cm from the atomic beam. The coherence length of the laser radiation was about 10 cm, that's why the interaction of atoms with the field of two counterpropagating light waves was coherent. The width of the strip atomic beam (a equals 0.02 cm) was much less than the distance to the mirror. The specific feature of the given setup is the use of pulsed laser radiation with the duration (tau) less than 1/(gamma) ((gamma) -1- the time of resonant level spontaneous decay), so the atoms are scattered only due to the induced light pressure force. In this paper the detailed investigation of the distance R influence on the scattering process was carried out. With this purpose the mirror was mounted at different distances from the atomic beam. (truncated)

Nikolai N. Bezuglov

G. Labeyrie, Robin Kaiser, Dominique Delande

Aldo Amodeo, V. Berardi, Roberta Capobianco +2 more

We have characterized experimentally the trapping of resonance radiation in an effusive He beam produced by a needle injector. In order to take into account the influence of secondary effects, such as collisions, on the trapping process, the measurements were carried out by investigating the line intensity dependence on the atomic density of transitions , and in the visible and and in the vacuum ultraviolet region of the helium spectrum. The comparison between visible and vacuum ultraviolet spectra allowed us to characterize the excitation process and to evaluate the contribution of collisional effects. We have calculated the escape factor, g, as a function of the atomic density and of the distance from the needle injector, i.e. along the beam path. The results were also compared with the Holstein and Phelps approach describing the trapping process in terms of an effective radius, . Our results show that in the case of an effusive beam, the effective radius is of the order of the effusive beam radius, namely .

Daniel F. Walls, Gerard J Milburn

Akifumi Takamizawa, Ryohei Hokari, Sota Kagami +5 more

A magneto-optical trap of cesium atoms was generated by applying a circularly polarized cooling laser beam onto a reflective two-dimensional diffraction grating with an aperture and by retroreflecting the incident beam passing through the aperture while reversing the circular polarization. The cooling laser beams comprised the incident, retroreflected, and four diagonally diffracted beams at an angle of 50° with respect to the normal direction of the grating surface. The intensity of the retroreflected beam was carefully adjusted to balance the radiation forces acting on the atoms. A significant number of cold atoms (7.0 × 106) were captured, in spite of the difficulty in a magneto-optical trap of cesium atoms, using nonorthogonal cooling beams owing to the high nuclear spin. The significance of the retroreflected beam in the trapping process was highlighted when the intensity of the retroreflected beam was reduced, resulting in the absence of trapped atoms. Notably, the cold atom cloud was generated near the edge of the region, where all the cooling beams were overlapped. The phenomenon is explained by the numerical calculations of the radiation forces considering all the Zeeman sublevels in the cooling transition and the Gaussian intensity profile of the incident beam.