Relaxation mechanism of optically pumped Rb vapor of high density in strong magnetic fields

The relaxation rates of the polarized rubidium. (Rb) vapor were measured by using a chopped pumping laser to investigate the depolarization. mechanism of a high density Rb vapor in a strong magnetic field. The measurement was carried out in a range of the magnetic field from 1 to 5 T and the Rb cell temperature from 90 to 130 degreesC which corresponds to the Rb vapor dens ity from 0.2 to 2.0 x 10(13) at./cm(3). The position dependence of the rela xation rates was also measured along the Rb cell axis. The experimental res ults showed that two components, i.e. a fast component with the relaxation rate of similar to 65 ms(-1) and a slow component with the relaxation rate of similar to1 ms(-1) contribute. The observed relaxation rates were analyz ed by the wall relaxation model, the effusion model and the radiation trapp ing model. It was found that the slow component was well explained by the w all relaxation and the effusion effect. On the other hand, the fast compone nt is due to a formation of the localized Rb polarization around the pumpin g laser by a radiation trapping effect and a subsequent relaxation process due to an effusion. (C) 2001 Elsevier Science B.V. All rights reserved.