We are here in Germany, at the Institute of Nuclear Physics of the Johannes Gutenberg University Mainz together with Josef Pochodzalla, who is leading the activity SPHERE in the framework of the HadronPhysics2 project of FP7. Could you perhaps briefly introduce yourself to the audience and tell us what MAMI is? 

My name is Josef Pochodzalla and I am an experimental physicist here at the University of Mainz. I started my scientific career at the Max Planck Institut of Nuclear Physics in Heidelberg. After my PhD I spent several years at the Michigan State University in the United States, at the University Frankfurt and at the Gesellschaft für Schwerionenforschung GSI in Darmstadt, Germany. About 10 years ago I came to the Institute of Nuclear Physics of the Johannes Gutenberg University Mainz.  At present I am the managing director of this institute which runs an electron accelerator called MAMI.


The acronym MAMI stands for the Mainz Mikrotron. It is one of the largest experimental facilities in Europe for basic research in the field of hadron and nuclear physics which is operated by a university. Actually MAMI is located right in the center of the campus here in Mainz.

Today I am working mainly on experiments at our accelerator here in Mainz, but I am also involved in experiments at CERN and at GSI. Furthermore I am also participating in the preparation of the PANDA experiment which is one of the biggest experiments at the international FAIR facility presently being constructed in Darmstadt.

Last but not least I am also spokesperson of the SPHERE activity of Hadronphysics3.

Josef, as you just said, you are involved in several experiments – not only here in Mainz. What is your personal motivation for this broad activity?

In essence nuclear physics research attempts to understand the nature of all manifestations of nuclear matter in our universe. Protons and neutrons form the tiny core of an atom. Even though they are very small compared to the size of an atom, atomic nuclei account for more than 99.9% of the mass of an atom and also of stars, planets as well as all living things on earth.

In the early years of nuclear physics research the composition of an atomic nucleus in terms of protons and neutrons, its structure and basic properties were in the spotlight. Studies were focused on the nature of radioactive decays, nuclear reactions, and the synthesis of new elements and isotopes.

Today we know that protons and neutrons are not elementary particles. They are built of three quarks each held together by a swarm of gluons. A proton consists of two so called up quarks and one down quark. A neutron is a combination of one up quark and two down quarks

Nowadays a nucleus is seen as a system of quarks and gluons that arrange themselves into protons and neutrons.  As a consequence the scope of nuclear science has broadened and extends from the today's fundamental particles - quarks and gluons - to the most spectacular of cosmic events like supernova explosions. Remnants of these cosmic catastrophes are neutron stars that have a core density ten times higher than normal nuclei.

Understanding from basic principles how the nuclear force binds protons and neutrons into stable nuclei or into neutron stars is one of the mysteries we want to solve by these activities.

You are leading the “SPHERE” activity – What are the scientifically exciting aspects of your research project?

If you want to see how fast a river flows you can throw a leaf into the water as a tracer. That means that an impurity in a system can make things better visible.


In the experiments I mentioned before we do the same thing with a nucleus. We replace one proton or one neutron by a special type of particle called a hyperon. The hyperon is so much like the neutron, with one major difference: instead of one up and two down quarks, the lightest hyperon contains a so called strange quark.together with one up and one down quark. These new type of nuclei are called hypernuclei.

That explains the acronym SPHERE which stands for Strange Particles in Hadronic Environment Research in Europe.

The fact that the hyperon is different from a proton or a neutron gives us a different handle on the strong interaction, because we see that it will do things a little differently, It's hoped that probing the nucleus with this impurity will provide new insights into the structure of matter.

Who is actually participating in SPHERE?

Addressing the fundamental question of the formation of nuclei and neutron stars from quarks and gluons is a long-term project and requires a concerted action between basic experimental and theoretical research along with the development of advanced detector technologies

SPHERE brings together the leading experts in the field of hypernuclear physics from all over Europe: the Czech Republik, Germany, Israel, Italy, Poland and Spain.

Theoretical groups come from Barcelona, Granada, Jerusalem, Prague, Torino, Valencia and Warszawa.

On the experimental side all major Experiments – the finished FINUDA at DAPHNE in  Frascati (which is still analyzing data), the HYPHI at the GSI Darmstadt, A1-KAOS at Mainz Mikrotron MAMI, and the planned PANDA experiment at the international FAIR facility in Darmstadt are represented in SPHERE.

Frequent meetings between the participants are key elements of SPHERE.




What do you want to achieve with this activity?

The goal of SPHERE is to maintain and further strengthen the relations among the participating experimental and theoretical research groups and thus to broaden and complement the existing and future research structures in Europe.

In this way SPHERE helps to make efficient use of the available resources.

In addition the network SPHERE itself serves as a partner for similar networks acting partially outside of Europe.

Since 2010 we have now annual joint meetings between the current network activity SPHERE and the "International Collaboration Platform for Strangeness Nuclear Physics by Electron Beams" supported by Japan Society for the Promotion of Science.


In which way can society eventually benefit from the activities of  SPHERE?

Many new technical inventions which were developed In the past, to perform basic research in physics are now part of our daily life.

For example, high energy heavy ion reactions studied at Berkeley in the United states or at the GSI in Darmstadt over more than 30 years are now a tool for cancer therapy. Of course, this application was not envisaged when this field of basic research was initiated.

SPHERE is driven by the scientific curiosity of the participating physicists working in the field of hypernuclei. The immediate impact or the direct applications of the scientific results of hypernuclear physics for society is at present difficult to predict. Basic research should be always considered as an investment in the future.

Nonetheless already now Europe benefits from the activity of SPHERE in several ways:

As a consequence of the joint meetings between SPHERE and the JSPS network, scientists from Japan and the United States joined the experimental program at Mainz. In this way SPHERE helped to develop new partnerships and to strengthen the role of Europe as part of the global scientific landscape.

Another direct benefit for society comes from the students we train and educate by performing this research within a European framework. These students get acquainted with Europe not only as a political and economic unity, but also as a social community. For this young generation – some of them will be future leaders in science and industry - borders within Europe do not exist anymore. By working in international partnerships and networks, this young generation will think European.

In general, why do you think should a young person choose to study science and why should they do so in Europe?

In the next decades human kind is facing several fundamental challenges like

  • Secure energy supply and  better energy-efficiency
  • Restraining  the climate change
  • Provide sufficient food and water for everyone

The development of new technologies will be crucial to address these serious problems. Innovative technologies often emerge from fundamental research. Therefore a continuous support of fundamental research will be a key element for our future.

With its high technical standard, Europe offers the ideal infrastructure for this kind of research. Complemented by the brain power of students I am sure that Europe wll play a crucial role in solving the problems our earth is facing.

The HadronPhysics3 project is supported by the European Union
under the 7th Framework Capacities Programme in the area of Research Infrastructures (RI).