High energy beam lifetime analysis

We have developed a positron lifetime defect analysis capability based on a 3 MeV electrostatic accelerator. The high energy beam lifetime spectromete r is operational with a 100 mCi Na-22 source providing a current of 5.5 x 1 0(5) positrons per second. Lifetime data are derived from a thin plastic tr ansmission detector providing an implantation time and a BaF2 detector to d etermine the annihilation time. Positron lifetime analysis is performed wit h a 3 MeV positron beam on thick sample specimens at counting rates in exce ss of 2000 per second. The instrument is being used for bulk sample analysi s and analysis of samples encapsulated in controlled environments for in si tu measurements. (C) 1999 Elsevier Science B.V. All lights reserved.