EXPERIMENTAL-STUDY OF POSITRON MOTION IN KAPTON

The drift of positrons under the action of an electric field in Kapton has been observed by using a variable-energy positron beam and the Do ppler broadening technique. Even if the maximum applied field (2 MV/cm ) is so high that the electrostatic work for a displacement of less th an 0.15 nm is larger than the thermal energy, the experimental data ca n be fit by the diffusion model with a field-independent mobility. The best-fit value of the mobility (ca. 1 x 10(-3) cm2 V-1 s-1) is extrem ely low in comparison with other dielectrics. The results are discusse d with regards to the interaction of positrons with the molecular fiel d.