Abstract:
The two quantities which can be observed by annihilation of an individual positron in condensed matter are the positron age τ which is the time interval between implantation and annihilation of the positron, and the momentum p of the annihilating positron-electron pair. Correlated measurements of these quantities (Age-Momentum Correlation, AMOC) are an extremely powerful tool for the study of reactions involving positrons. It not only provides the information obtainable from the two constituent measurements but allows us to follow directly, in the time domain, changes in the positron-electron momentum distribution of a positron state (e.g., positronium slowing-down, cf. Sect. 3.3) or transitions between different positron states (e.g., trapping of positrons, cf. Sect. 3.2, chemical reactions of positrons and positronium, cf. Sec. 3.1, or self-localization of positronium from a metastable positronium state in liquid rare gases, cf. Sect. 3.4). So far AMOC measurements have only been performed at MeV positron beams [1,2]. It is highly recommended that the advantage of the beam-based AMOC technique should be applied to keV positron beams, too.Keywords:
Positronium
Annihilation
Momentum (technical analysis)
Metastability
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