Optimization of positron lifetime spectrometer using Monte-Carlo simulation of the detectors
The lifetime of ortho-positronium (o-Ps) formed in zeolites, low-k dielectrics and thin porous layers may reach a significant fraction of the 142 ns vacuum o-Ps lifetime. In these materials a large part of the measured signal originates from electron-positron annihilation resulting in 3 photons. This is also the case in the study of porous thin layers with high o-Ps re-emission probability. The precise evaluation of the intensity of these lifetime components is challenging due to the difference between the detection efficiency of the 2γ and 3γ annihilation events in the lifetime spectrometer. As the experimental determination of the detection efficiencies is difficult, numerical simulation of the spectrometer system can yield valuable information. We performed Monte-Carlo (MC) simulation using the GEANT4 package 1 to determine the detection efficiencies in a slow positron beam-based lifetime spectrometer at CERN, specially designed to measure orthopositronium re-emission efficiency from surfaces and porous layers.
U.Gendotti P.Crivelli L.Liszkay P.Perez A.Rubbia
Institut für Teilchenphysik,ETHZ,CH-8093 Zürich,Switzerland CEA Saclay,IRFU,91191 Gif-sur-Yvette Cedex,France
国际会议
第九届国际正电子与正电子素国际会议(9th International Workshop on Positron and Positronium Chemistry)(PPC–9)
武汉
英文
54
2008-05-11（万方平台首次上网日期，不代表论文的发表时间）