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| Titel |
Results from the CERN pilot CLOUD experiment |
| VerfasserIn |
J. Duplissy, M. B. Enghoff, K. L. Aplin, F. Arnold, H. Aufmhoff, M. Avngaard, U. Baltensperger, T. Bondo, R. Bingham, K. Carslaw, J. Curtius, A. David, B. Fastrup, S. Gagné, F. Hahn, R. G. Harrison, B. Kellett, J. Kirkby, M. Kulmala  , L. Laakso, A. Laaksonen, E. Lillestol, M. Lockwood, J. Mäkelä, V. Makhmutov, N. D. Marsh, T. Nieminen, A. Onnela, E. Pedersen, J. O. P. Pedersen, J. Polny, U. Reichl, J. H. Seinfeld, M. Sipilä, Y. Stozhkov, F. Stratmann, H. Svensmark, J. Svensmark, R. Veenhof, B. Verheggen, Y. Viisanen, P. E. Wagner, G. Wehrle, E. Weingärtner, H. Wex, M. Wilhelmsson, P. M. Winkler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 4 ; Nr. 10, no. 4 (2010-02-15), S.1635-1647 |
| Datensatznummer |
250008107
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| Publikation (Nr.) |
 copernicus.org/acp-10-1635-2010.pdf |
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| Zusammenfassung |
| During a 4-week run in October–November 2006, a pilot experiment was performed
at the CERN Proton Synchrotron in preparation for the Cosmics Leaving
OUtdoor Droplets (CLOUD) experiment, whose aim is to study
the possible influence of cosmic rays on clouds. The purpose of the pilot experiment
was firstly to carry out exploratory measurements of the effect of ionising particle
radiation on aerosol formation from trace H2SO4 vapour and secondly to
provide technical input for the CLOUD design.
A total of 44 nucleation bursts were produced and recorded, with formation rates
of particles above the 3 nm detection threshold of between 0.1 and 100 cm−3s−1,
and growth rates between 2 and 37 nm h−1. The corresponding H2O
concentrations were typically around 106 cm−3 or less.
The experimentally-measured formation rates and \htwosofour concentrations
are comparable to those found in the atmosphere, supporting the idea that
sulphuric acid is involved in the nucleation of atmospheric aerosols. However,
sulphuric acid alone is not able to explain the observed rapid growth rates,
which suggests the presence of additional trace vapours in the aerosol chamber,
whose identity is unknown. By analysing the charged fraction, a few of the
aerosol bursts appear to have a contribution from ion-induced nucleation and
ion-ion recombination to form neutral clusters. Some indications were also
found for the accelerator beam timing and intensity to influence the aerosol particle formation
rate at the highest experimental SO2 concentrations of 6 ppb, although
none was found at lower concentrations.
Overall, the exploratory measurements provide suggestive evidence for ion-induced
nucleation or ion-ion recombination as sources of aerosol particles. However in
order to quantify the conditions under which ion processes become significant,
improvements are needed in controlling the experimental variables and in the
reproducibility of the experiments.
Finally, concerning technical aspects, the most important lessons for the CLOUD
design include the stringent requirement of internal cleanliness of the aerosol
chamber, as well as maintenance of extremely stable temperatures (variations
below 0.1 °C |
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