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Dieter Ackermann - Partaking the Construction of a New Accelerator

Dr. Ackermann is a German senior researcher, specialized in Super-Heavy Element Physics. He is currently holding a position at CEA/GANIL (Large Heavy Ion National Accelerator) in the framework of the development of the new spectrometer S3 for nuclear structure research. He has been working at GANIL in Caen (Normandy, France) since May 2015; his Enhanced Eurotalents fellowship ends in 2018. ​

Published on 28 November 2016
  • What were you doing before coming to CEA? How did you get the opportunity to come to GANIL?

For the last fifteen years, I have been working in a German accelerator laboratory in Darmstadt called GSI Helmholtz Centre for Heavy Ion Research. More specifically, I have been focusing on heavy and super-heavy nuclei (SHN).

My research project is entitled "Exploring Super Heavy Elements at SPIRAL2–S3 - Nuclear Structure, Reaction Dynamics and Astrophysical Relevance". My motivation to come to GANIL was twofold and the major background for this is the fact that for the research on SHN high intensity beams with a high duty cycle, i.e. with a continuous time structure are needed. Such an accelerator is presently being built at GANIL in the framework of the SPIRAL2 project. At my home institution, GSI, a large scale project, called FAIR (Facility for Antiproton and Ion Research), is presently being constructed. For that purpose a new pulsed accelerator scheme with low repetition rate and high intensities concentrated in very short beam bursts will replace the old long duty cycle capabilities, making SHN research with this machine impossible. The time when this will be implemented is not clear yet. It will possibly happen between 2020 and 2022. At GANIL, in addition to the optimal beam conditions, the separator-spectrometer set-up S3 (Super Separator Spectrometer) has been discussed and developed throughout the last 10 years. SHN research is one of its mayor research fields. It is presently being constructed and will be commissioned in 2018. I was following its development from the beginning and participated in launching several letters of intent for SHN synthesis and nuclear structure studies at S3 in 2009 and 2012. This facility with its combination of a high intensity continuous waves (CW) accelerator and the highly efficient separator S3 will provide optimal conditions for my research field. In addition the GSI accelerator is shut down until 2018 in order to prepare the facility for FAIR. As I was collaborating with GANIL since I came back from Italy in 1999, it seemed to be the right time now to actually work there for a while. In this situation, when my colleagues in Caen asked me "Why don't you come?" – I obviously agreed. Somebody had found out about the Enhanced Eurotalents programme dedicated to the international mobility of postdoctoral and senior researchers, I applied and obtained the fellowship!

The goal of my present stay at GANIL is to develop the physics case to be studied with the new facility. The main subjects are the study of the nuclear structure of superheavy nuclei and the reaction mechanism leading to their synthesis in fusion of colliding heavy ions. While my focus is on SHN, the new techniques employed also at S3 like precise mass measurements giving access to nuclear binding energies and laser spectroscopy revealing the atomic structure of those very heavy systems will be very profitable for our research field.

If in view of the FAIR preparations GSI will be back to normal accelerator operation by 2018, my last year at GANIL, I might go back to Germany then. However, the perspectives would be rather short term, given the implementation of the short pulse mode soon after. The way out would be a new CW accelerator dedicated to our research, which we are pursuing for many years. However, presently I think it would be more profitable to stay in Caen for my personal activities, given the opportunities which will most likely be offered by SPIRAL2, being ready soon, according to the actual planning.

We will be operating in a very wide range of activities, from nuclear spectroscopy (for lighter and heavy nuclei) to nuclear astrophysics (with low-energy equipment). All these activities require a lot of beam time but it's worthwhile I think. For the time being I learn a lot about all the procedures and capabilities of GANIL and its accelerator and experimental infrastructure – it's fascinating. A lot of stimulation for our work comes also from our close collaboration with cutting-edge institutes in France, like the CEA/IRFU (Research Institute  of Fundamental Laws of the Universe), Orsay's IPN (Nuclear Physics Institute) and CSNSM (Centre de Sciences Nucléaires et de Sciences de la Matière), and the IPHC (Institute Pluridisciplinaire Hubert Curien) in Strasbourg.

  • How many employees are working at GANIL? How big is your work team?

At GANIL, we are about 250 people (researchers, engineers and technicians). The lab is welcoming scientists from all over the world: Germany, Belgium, Italy, USA, Japan... I am coordinating a small physics team of about 8 people. We are organizing workshops, meetings and conferences. We recently went to Italy to a conference, which generated a great deal of publicity for the laboratory: it gave us the opportunity to exchange with other scientists, discussing the project in a dedicated session and ultimately shaping it further.

  • How is the project going so far?

The project is going well I would say: we have delays that I would define as normal in any research project. These delays are also linked to safety files – French bureaucracy can be tricky to navigate at times. Just like nuclear power plants, our facilities require a lot of administrative processes and it takes time to go through them.

Very recently we had our first laser spectroscopy experiments on the heaviest nuclei at my home institution under the lead of my young colleagues there which even resulted in a publication in the magazine Nature

  • What are the strengths of your stay at CEA?

Working for the development of a new facility is very exciting; this is a unique opportunity.

There are also a number of advantages linked to my private life that I enjoy a lot here in France. I rented a house on the coast in Ouistreham. Of course, I love country and culture, the food, the wine… the beer even! As a German, I appreciate the variety offered in France. In Germany, we are proud of our quality beer but they tend to be monolithic.

  • Do you think the French and the German scientists have a different approach to research?

In the past, one difference that always struck me about research in France compared to Germany was the definition of a physicist: in Germany or in Italy for that matter, physicists have both theoretical and practical skills. They operate in very technical hands-on. In France, a physicist had a rather intellectual approach, focusing more on the theoretical aspect of research. Technology was mainly handled by engineers. This could sometimes hinder the conduction of a research: between physicists we organize shifts so that experiments never stop. Engineers typically have fixed working hours and go home after their working day. In the past there were situations when we get stuck due to this. This has changed a bit over the years though; it is less and less the case. In addition, at GANIL, scientists come from all over the world as in many laboratories in Europe of the same kind. The working style is nowadays pretty much the same everywhere. Physics-wise, the equipment and the technological capabilities in France are of high quality, just like in Germany.