Research - ARIBE, a Low Energy ion facility

The Caen-based CIRIL (Centre Interdisciplinaire de Recherche Ions Lasers, interdisciplinary center for ion-laser research) is a joint (CEA, CNRS, ENSICAEN, Caen Basse-Normandie University) laboratory that conducts interdisciplinary ion beam research at GANIL (Grand Accélérateur National d'Ions Lourds, the French large heavy-ion accelerator).

CIRIL's new facility called ARIBE (Accélérateurs pour les Recherches avec les Ions de Basses Energies, accelerators for low energy ion research) was recently inaugurated by François Goulard, Minister Delegate in charge of Higher Education and Research. ARIBE is a platform dedicated to interdisciplinary low energy ion research. The facility also clears the way for vast field of research and innovation ranging from atomic physics to biology and from nanotechnologies to surface treatments.
At low energies multi-charged ions interact through multiple electronic capture processes that cause very strong disturbances in the electronic system of matter. The main consequences are molecular dissociation, aggregate fragmentation, particle emission and surface alterations. Their mechanisms are poorly known although they are important for basic research in different fields as well as for areas of applied research. ARIBE, a platform dedicated to interdisciplinary low energy ion research, and its two ion sources and different beam lines now provides researchers with an efficient tool for broadening their knowledge of the mechanisms, thanks to ongoing efforts by Bernd Huber and his team. "ARIBE is in an area where until now the facilities only used low charged ions. We will have heavily charged ions, in other words we'll be adding another parameter, i.e. potential ion energy. This will be an additional means for studying ion-excitation of electrons and for altering surfaces without changing the deep inner material," summed up CIRIL Director Serge Bouffard. This means interesting applications especially in microelectronics.

Three Systems

ARIBE has three systems called LHI (Ligne de faisceaux Haute Intensité, high intensity beam line), LTBE (Ligne de Très Basse Energie, very low energy line), and LAST (Ligne d'Agrégats Sélectionnés en Taille, size selected aggregate line). LHI has seven stations for conducting heavy experiments such as ion-aggregate collisions over long periods. It delivers heavily charged high intensity ions since the accelerator can cover an energy range from 5keV to 25keV per charge. The LTBE is optimized to deliver multi-charged ion beams at energies as low as 1eV per charge. In the area of speed, ion interaction with matter is determined by the potential energy of multi-charged ions. Therefore, the interaction phase with insulated surfaces or metallic or semiconductor aggregates occurs during 'contactless' collisions. Researchers' challenge is to decelerate a 20kV beam by a factor of 20,000 while preserving the optic properties of the beam.

LAST provides size selected aggregate beams and, therefore, clears the way for new applications with the accelerator. LAST can actually provide metallic or semiconductor aggregate beams at energies ranging from a few eV to several keV. The metal or semiconductor is pulverized by a 'magnetron' discharge and the emitted atoms condense in a helium atmosphere that has been cooled to the temperature of liquid nitrogen. The charged aggregates are then separated by a 'flight time' system and an electrostatic quadrupole. "The aggregates will be used as complex targets for basic research. After strong deceleration, they can also be deposited on substrates or into matrixes for the study of their interaction with the environment or for the design of new nanostructuration methods," explained CIRIL Director. He added that they are planning to "develop beams of molecules with biological potential for the surface treatment of materials used in medicine."

From Silicon to DNA

ARIBE will let biologists take a closer look a a small piece of DNA, for instance adenosine monophosphate. When an atom collides with this molecule, it breaks up producing phosphates and adenine, the molecule having lost oxygen. "It is interesting to observe the role of water in the fragmentation. For instance, if you have two or ten molecules of water around an adenosine monophosphate molecule, fragmentation is the same. On the other hand, if you put twenty water molecules, no fragmentation occurs during collision. You only observe the emission of water molecules. So, they are protecting the adenosine monophosphate molecule. These findings could interest radio biology among others," explained Serge Bouffard.

ARIBE also makes it possible to conduct an experiment where heavily argon (that has lost 17 electrons) charged ions are brought close to a clean silicon surface with an oxydation protection hydrogen layer. The silicon surface is bared and reacts when exposed to ambient air. "Small silicon dioxide beads then form on its surface. In other words, the silicon surface can be 'nanostructured'. The point is to be able to place the beads where we want. We are thinking of setting up a collaboration with a Japanese group that has begun to control the technology consisting of manufacturing particle nanobeams, to place the ions the way we want with a precision of a few nanometers," stated CIRIL Director. Another possible ARIBE application would be the simulation of what happens in fusion reactors, specifically for the ITER program. "We can simulate plasma-wall interaction and determine the mechanisms that lead to wall erosion. This is one of the greatest problems in fusion reactors. So, we have filed an proposal with the ITER authorities to take measurements with ARIBE beams."

Part of a European Infrastructure

Similar to SPIRAL but on another scale, ARIBE is very high quality equipment that puts the GANIL and CIRIL in an excellent position for the study of multi-charged slow ion interactions with matter. The research facility is part of LEIF, a European distributed infrastructure coordinating the activities of five European low energy ion infrastructures in five different countries i.e. Germany (MPIK Heidelberg), Denmark (University of Aarhus), France (CIRIL), the Netherlands (KVI) and the United Kingdom (Queen's University of Belfast). Under the Sixth Research and Development Technology Program, the activity is backed by the ITS LEIF Project (2006-2009: Ion Technology and Spectroscopy at Low Energy Ion Beam Facilities) that brings together 32 research groups (infrastructures and users, laboratories and industry) from 18 European countries. Project goal is to promote transnational access to low energy multi-charged ions, initiate joint technological developments to guarantee the highest level of instrumentation and infrastructures, and improve communication and staff and equipment exchange. Actually Network Coordinator Bernd Huber works at... CIRIL !

Contact :
CIRIL - http://www.ganil.fr/ciril
Serge Bouffard, CEO - [e-mail]
Phone [phone] - Fax [phone]

Source : ScienceTech Basse-Normandie Newsletter
http://www.basse-normandie.net/lettre/index_en.html

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