MAGNETICALLY ASSISTED SISYPHUS EFFECT

This paper presents an experimental and theoretical study of laser coo ling in a standing wave in the presence of a small transverse magnetic field (Magnetically Assisted Sisyphus Effect: MASE). The analysis is worked out for a J(g) = 1 to J(e) = 1 transition corresponding to the experiment performed on the 2(3)S(1) <----> 2(3)P(1) transition of met astable helium. In this situation, MASE has an effect opposed to the u sual Doppler cooling effect, i.e. it produces heating for a negative d etuning. Depending on the various parameters, the competition between MASE and Doppler cooling, which act on different velocity ranges, lead s to interesting new effects, such as a bistable force. The velocity d ependence of the total force is calculated, using a semi-classical app roach. A second theoretical treatment, where the atomic motion is quan tized, is used to study the time evolution of the velocity distributio n. The results of these calculations are compared to experimental obse rvations.