We present the results of a global irradiation test of full size triple-GEM detectors operated with CF
4-based gas mixtures. This study has been performed in the framework of an R&D activity on ...detectors for the innermost region of the first muon station of the LHCb experiment. The prototypes have been irradiated at the Calliope facility of the ENEA-Casaccia with a high intensity 1.25 MeV
γ
60Co source. After the irradiation test the detectors performances have been measured with X-rays and with a 3 GeV pion beam at CERN. A SEM analysis on several samples of the detectors has been performed to complete the understanding of the physical processes occurring in a GEM detector during a strong irradiation.
We report the results of a systematic study of the time performance of triple-GEM detectors operated with several gas mixtures which are new for this kind of detectors. This study was performed in ...the framework of an R&D activity on detectors for the level 0 LHCb muon trigger. We show that a considerable improvement, with respect to the traditional gas mixture Ar/CO/sub 2/(70/30), is obtained with the fast and high yield based CF/sub 4/ and iso-C/sub 4/H/sub 10/ gas mixtures; time resolutions better than 5 ns. Discharges studies have been performed with high intensity pion/proton beams at the /spl pi/M1 beam facility of the Paul Sherrer Institute (PSI). The results show that the operation of the detector is very stable, if a small fraction of iSO-C/sub 4/H/sub 10/ or a large amount of CF/sub 4/, is used. The role of the electron diffusion in the formation of discharges, has been studied testing two different detector gap geometries.
In this paper results of a time performance study of triple-GEM detectors are discussed. This study was driven by an R&D activity on detectors for the Level 0 LHCb muon trigger. Results presented in ...this paper are of more general interest, i.e. for experiments in which high-rate charged-particle triggering is needed. Little interest was given so far to time performance of GEM detectors. Only one paper (Bressan et aL, NIMA 425 (1999) 262.), presented measurements of double-GEM detector time resolution with an Ar/CO/sub 2/ (70/30) gas mixture. The authors of the paper quoted a resolution for the double-GEM detector such that high efficiency muon triggering at LHCb would be impossible. The results reported, obtained with the addition of CF/sub 4/ and/or isobutane to the Ar/CO/sub 2/ standard mixture, considerably improve the time performance discussed in the above mentioned paper and make the triple-GEM detector a promising option for high-rate charged-particle triggering.
AMADEUS is an experiment planned to be performed at the DAΦNE e+e− collider of the Frascati National Laboratories (Italy) of INFN, to investigate the antikaon-nuclei interaction at low energies. ...AMADEUS will perform, for the first time, full-acceptance studies of antikaon interaction in light nuclei, including a complete experimental program for the case of the kaonic nuclear clusters. The study of the absorption of antikaon by the nucleus will provide information concerning the \documentclass12pt{minimal}
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\begin{document}$\bar{K}N$\end{document} interaction and the modification of the kaon mass in the nuclear medium. The experiment is being preceded by the study of the hadronic interactions of K− in the 4He of the drift chamber from the KLOE experiment data.
The SIDDHARTA experiment measured the kaonic 3He and 4He 3d →2p X-ray transitions using gaseous targets for the first time. The strong-interaction shift both of the kaonic 3He and 4He 2p states was ...determined with a precision of a few eV. The shift of kaonic 4He is much smaller than the values obtained in the experiments performed in 70’s and 80’s, while it is consistent with the recent result of the KEK E570 experiment, as well as the theoretical calculated values. Therefore, the problem on kaonic helium (the “kaonic helium puzzle”) was definitely solved. The first observation of the kaonic 3He X-rays was also achieved in the SIDDHARTA experiment. The shift both of kaonic 3He and 4He was found to be as small as a few eV.
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\begin{document}$\overline{K}N$\end{document} system at rest plays a key role for the understanding of strong interaction of hadrons with strangeness involved. The experiment SIDDHARTA used X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. It was the first experiment on kaonic He3 and deuterium ever, kaonic hydrogen was measured with improved precision resulting in \documentclass12pt{minimal}
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\begin{document}$\epsilon_{1s} = -283 \pm 36 \mbox{(stat)} \pm 6 \mbox{(syst)}$\end{document} eV and \documentclass12pt{minimal}
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\begin{document}$\Gamma_{1s} = 541 \pm 89 \mbox{(stat)} \pm 22 \mbox{(syst)}$\end{document} eV. Additionally a scheme for an improved future experiment on kaonic deuterium is introduced in this contribution.
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