MEASUREMENTS OF TEMPERATURE AND SPRING CONSTANT IN A MAGNETOOPTICAL TRAP

We have measured the low-density characteristics of a magneto-optical trap for both isotopes of rubidium. Trapped-atom temperatures are meas ured by the time-of-flight technique and are similar to temperatures i n optical molasses. They are below the Doppler limit in most cases and increase linearly with the ratio of laser intensity to laser detuning . A slight difference between the two isotopes is observed. The data a gree well with three-dimensional, multistate, semiclassical simulation s. Spring constants of the trap are inferred from careful measurements of the size of the trapped-atom cloud. The spring constant is seen to increase with intensity at low intensity, becoming independent of int ensity at high intensity. This trend is consistent with sub-Doppler co oling mechanisms.