  The scattering of Rb atoms on an anti-relaxation coating was studied. No
significant change in the spin relaxation probability of Rb atoms by single
scattering from a tetracontane surface was observed by cooling the film from
305 to 123 K. The mean surface dwell time was estimated using a time-resolved
method.Delay-time spectra, from which mean surface dwell times can be
estimated, were measured at 305, 153, and 123 K, with a time window of
$9.3\times 10^{-5}$ s. The increase in mean surface dwell time with cooling
from 305 to 123 K was smaller than $4.4\times 10^{-6}$ s, which is
significantly smaller than the value expected from the mean dwell time at room
temperature measured using the Larmor frequency shift. These results can be
explained by assuming a small number of scattering components, with a mean
surface dwell time at least three orders of magnitude longer than the majority
component.
