  Using several source models, we analyze the transverse momentum dependence of
HBT radii in the relativistic heavy-ion collisions. The results indicate that
the single-particle space-momentum angle distribution plays an important role
in the transverse momentum dependence of HBT radii. In a cylinder source, we
use several formulas to describe the transverse momentum dependence of HBT
radii and the single-particle space-momentum angle distribution. We also make a
numerical connection between them in the transverse plane.
