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 spectrometer is operational with a 100 mCi 22Na source providing a current of 5.5=105 positrons per second. Lifetime data are derived from a thin plastic transmission detector providing an implantation time and a BaF2 detector to determine the annihilation time. Positron lifetime analysis is performed with a 3 MeV positron beam on thick sample specimens at counting rates in excess of 2000 per second. The instrument is being used for bulk sample analysis and analysis of samples encapsulated in controlled environments for in situ measurements. q1999 Elsevier Science B.V. All rights reserved