Alternative to the hyperfine-change-collision interpretation for the behavior of magneto-optical-trap losses at low light intensity

Usually, the large trap loss rates observed in MOTs at the low light intens ity regime have been associated with hyperfine change collisions (HCC). We propose an alternative mechanism to explain the sudden raise up of trap los s rates at low intensity without relying on HCC. Using the Gallagher-Pritch ard model [Phys. Rev. Lett. 63, 957 (1989)] together with an intensity depe ndent escape velocity, we were able to reproduce qualitatively well some ex isting experimental results, including recent observations by Nesnidal et a l. [Phys. Rev. A 62, 030701(R) (2000)]. This result reopens the discussion in order to better understand the physical mechanisms and their actual cont ribution to the trap losses.