Pulsed slow positrons were produced using a time-varying moderator bias with an interval of 82 ns; 97% of the positrons were
compressed within 2 ns width at the target position. Both the positron annihilation lifetime and Doppler broadening of the
positron annihilation radiation (DBPR) of polytetrafluoroethylene (PTFE) were measured as a function of the incident energy
of slow positrons. It was shown that the lifetime and intensity of the long-lived component of positron annihilation are independent
of the positron incident energy above 1.2 keV. However, the width of the Doppler-broadened annihilation γ-ray increased in
the energy region below 1.2 keV.