Positron lifetime spectroscopy
Positron lifetime spectroscopy is a technique in material science used for studying the types and concentrations of atomic sized defects in materials.
Positron sources
Typically positrons are produced through Beta Decay. A typical source would be 22Na, sodium-22.
Positron behaviour in materials
Typically positrons will thermalize, slow down, very quickly in a material. This means that they barely penetrate the surface of most materials. After thermalization, the positron will diffuse around the material, interacting with any defects, electromagnetic distortions or potential wells, they encounter. This may result in a change of the positron's state, collapsing its wave function and reducing the instantaneous chance of electron-positron annihilation. This will change the characteristic lifetime (in some ways similar to mean lifetime of the positron, which affects the lifetime spectra produced in experiment.
Simulation
Recently a program named SimPL has been produced at the University of Prince Edward Island, Prince Edward Island, Canada, which attempts to simulate the positron interaction and model the output spectra.