Interview: Yoshiki Tanaka on the trail of exotic atoms

Yoshiki Tanaka at WASA detector. © J. Hosan/GSI/FAIR

The researchers at GSI and FAIR come from all over the world. Young scientists in particular like to take advantage of the opportunity to go deeper into science at the Darmstadt research center. Among them is Yoshiki Tanaka, a Japanese physicist and winner of the FAIR GENCO Young Scientist Award in 2017, who recently conducted experiments with the WASA detector at the GSI/FAIR accelerator facilities. In an interview he talks about his work, his love of physics and his life in Germany.
Interview by Eva Sauer, Sofie Schnepf and Clara Schuler, who are studying “Science – Media – Communication” at the Karlsruhe Institute of Technology (KIT). As part of the course “Media and Public Relations”, in which KIT and GSI/FAIR cooperate, students conducted interviews with young researchers at GSI/FAIR.

When did your interest in science start and how did you become a scientist?
I have been interested in mathematics and science since primary school. In high school, when I had my first physics course, my fascination with the field began. There are just a few principles in the basic of mechanics that can be used to calculate almost everything. That impressed me so much that I decided to go to university to study physics.

You studied at the University of Tokyo. How did you come to GSI/FAIR in Germany?
At the University of Tokyo, I joined a group led by Prof. Ryugo Hayano. His group had been working with GSI/ FAIR since the 1990s to study special atoms called “deeply-bound pionic atoms”. After I had joined his group, we just launched a new experiment at GSI/FAIR, and I decided to work on various developments for this new experiment as a PhD student.

What do you appreciate about GSI/FAIR?
Because of the excellent experimental facilities at GSI/FAIR, it is very interesting to work here. The biggest advantage is that all the equipment I need for my experiments is right on the premises. If I want to test something, I can go there immediately and start. GSI/FAIR is a great place for me to concentrate fully on my research and experiments.

Are there things you don’t like about your work?
My work consists of many different activities, such as detector development, computer simulations, programming, electronics, cryogenics, and so on. Fortunately, I like all of them, and I can enjoy everything.

When you are not working, what do you like to do in your free time?
When I have time, I do different kinds of sports. At school I used to do a lot of long-distance running. Today I like to go snowboarding. Before the Corona crisis, I went on holiday to some ski resorts in Austria and Switzerland. I also started archery in Germany.

What is it like for you to live so far away from your home and family?
It’s sometimes a problem for me because Japan is far away and I can’t fly home quickly. The flight takes a long time and is very expensive. I usually fly home twice a year, once in summer and once in winter.

How would you summarize your research in one sentence?
My research focuses on studying exotic atoms and nuclei. Unlike ordinary atoms consisting of protons, neutrons, and electrons, exotic atoms we study include a meson, which is a pair of quark and antiquark. Such exotic particles are unstable, but we can produce them and investigate their properties by using accelerator facilities like GSI/FAIR. Studying these exotic particles will give us a hint to understand the origin of mass of the matter in the universe.

What do you hope to achieve with your ongoing experiments?
In the currently ongoing experiment at GSI, we search for exotic nuclei called η’-mesic nuclei with a very high experimental sensitivity. One of the key features and challenges in the experiment is to combine the large WASA detector system with the high-resolution spectrometer FRS at GSI. This unique combination will give us a very high experimental sensitivity, and we hope to observe the η’-mesic nuclei for the first time in the world.

You won the Young Scientist Award in 2017. Which of your research was awarded?
It was given to my PhD thesis about our experiments carried out at GSI in 2014. We performed the first experimental search for η’-mesic nuclei. We did not observe η’-mesic nuclei in an energy region predicted by a certain theory, but therefore we succeeded to give a stringent constraint on the η’- meson property from the experimental side.

Where do you see yourself in 10 years?
It is difficult for me to predict where I will be after 10 years. It may be GSI/FAIR or institutes in Japan, but it may be somewhere else. In general, I want to be flexible in terms of institutions and want to perform research at a place which is most suitable and the best for achieving the goals. After the just finished experiments at GSI, I hope that we can get many good results, and based on those results I would like to set the next goals.