https://doi.org/10.1140/epjd/e2012-20637-0
Regular Article
Thermal production of positronium in porous alumina
1
LNESS and Dipartimento di Fisica, Politecnico di
Milano, Via Anzani
42, 22100
Como,
Italy
2
Istituto Nazionale di Fisica Nucleare,
Via Celoria 16, 20133
Milano,
Italy
3
State Key Laboratory of Functional Materials for Informatics,
Shanghai Institute of Microsystem and Information Technology, Chinese Academy of
Sciences, 865 Changning
Road, 200050
Shanghai, P.R.
China
a e-mail: fabio.moia@polimi.it
Received:
1
November
2011
Received in final form:
26
January
2012
Published online:
17
May
2012
A porous anodic alumina sample with ordered channels was studied in order to characterise its efficiency as a positron-positronium converter at cryogenic temperatures. The effects of gas adsorption were found to be vacuum dependent and considerable up to 200 nm depth inside the sample. At higher depths it was possible to identify a temperature dependent positronium formation mechanism and the related activation energy was determined to be in an interval from 8.7 to 16 meV. Because of this mechanism the Ps yield decreases to a few percent with decreasing temperature and it can be considered unsuitable for an efficient cryogenic positronium production.
Key words: Topical issue: Electron/Positron Collision. Guest editors: Michael Brunger, Anne Lafosse, Gaetana Laricchia, Paulo Limao-Vieira and Nigel Mason
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2012
