Bulk defect analysis with a high-energy positron beam

摘要

A program using a positron beam to probe defects in bulk materials has been developed at Lawrence Liivermore national Laboratory, Positron annihilation lifetime spectroscopy (PALS) provides non-destructive analysis of average defect size and concentration. A 3MeV positron beam is supplied by Sodium-22 at the teminal of a Pelletron acceleragor. The high-energy beam allows large (>=1 cm~2) engineering smaples to be measured in air or even sealed in an independent environment. A description of the beam-PALS system will be presented along with a summary of recent measurements.