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PLRF 19 code for fitting of positron lifetime - binaries are available for download.

Positron annihilation

Positron is an antiparticle to electron and in solid matter it is annihilated by an electron. The annihilating electron-positron pair is transformed predominantly into two approximately anti-colinear annihilation gamma rays, which carry information about the annihilation process. There are three most important observables related to positron annihilation:

  • positron lifetime
  • Doppler shift in energy of annihilation radiation
  • deviation of annihilation gamma rays anti-colinearity

Positron annihilation spectroscopy (PAS) is a powerful technique providing a unique information about open-volume lattice defects. PAS is used in solid state physics and materials science as extremely useful tool for characterization of lattice defects.

PAS enables

  • characterization of defect on atomic scale
  • very high sensitivity to open volume defects (e.g. vacancies, vacancy clusters, dislocations etc.)
  • type of defects and defect densities can be determined, chemical environment of defects can be characterized by coincidence Doppler broadening studies
  • selective sensitivity to open volume defects only
  • non destructive testing
  • no special requirements for sample preparation (no special surface treatment, etc.)
  • experimental results can be directly compared with first-principles theoretical calculations

A brief introduction to PAS can be found in the Doctoral thesis of Jakub Čížek, Charles University 2001.