MeV positron beams

High-energy ( MeV) monoenergetic positron beams have been built and used in recent years. MV accelerators used in this work have been of Pelletron or Van de Graaff type. Source-free lifetime measurements in a 

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Simultaneous measurement of positron lifetime and the momentum of the annihilating pair can give information on thermalisation and transitions between positron states (and hence on chemical reactions of positrons or Ps). The most recent version uses MeV positron beams [35]. A full description of AMOC can be found elsewhere in this volume. 

Speed and performance of positron age-momentum-correlation (AMOC) measurements have been improved significantly by using an MeV positrons beam and by taking advantage of the beam-based p+yAf r-coincidence technique [1-5]. 

The authors would like to thank all of those who were involved in the Stuttgart MeV positron beam. This paper would not have been possible without the work of all of them. In particular we would like to thank Prof. A. Seeger for his continuous support, Dr. P. Bandzuch for providing us with the Xe data, Prof. H. D. Carstanjen and Dr. J. Major for many fruitful discussions, and Aleksandar Puzic for his help in preparing the manuscript. 

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