Professor Emeritus Akira Yamamoto receives high Japanese Order

Professor Emeritus Akira Yamamoto of KEK was awarded the Order of the Sacred Treasure, Gold Rays with Neck Ribbon, by the Emperor of Japan in recognition of his many years of distinguished service in particle physics during the 2023 Japanese spring conferment. This Order is awarded to persons who have been engaged for many years in the public service.

Prof. Yamamoto has been instrumental in the development of superconducting magnets and the application of low-temperature technology since its early days, playing a central role in the development of superconducting magnets for the Topaz experiment at the Tristan accelerator in Japan, the Balloon-borne Experiment with a Superconducting Spectrometer (BESS), the Large Hadron Collider (LHC) and the ATLAS experiment at the European Organization for Nuclear Research CERN. The technology established by Prof. Yamamoto is indispensable for current accelerator experiments. He had already been awarded the Medal with Purple Ribbon in the spring of 2016 for these achievements.
In this article, we present an interview with Prof. Yamamoto about his achievements and thoughts.
The roles of “electric field” and “magnetic field” are essential to handle accelerator particle beams. Prof. Yamamoto’s research career began with research on using electric fields.
“The first effort at KEK was to develop a technique for sorting particles using a high electric field. Various particles produced secondarily by the accelerator can be sorted and separated according to their velocity by passing them through a high electric field. At the time, K mesons were the focus of KEK accelerator and physics experiments. It was crucial to provide a beam of high purity by sorting and separating them from other particles. This development made it possible to provide a high purity, high-quality beam of K mesons, rarely produced and decay quickly, to physics experiments. The results of this research became my doctoral dissertation.”
In 1977, KEK launched the superconducting technology development project. Prof. Yamamoto became involved in research on superconducting magnets.
An example of his early work, an actual superconducting magnet for the Topaz experiment at the Tristan accelerator, which Prof. Yamamoto played a central role in developing, is on display in front of the KEK Cryogenics Center.
When conducting a collider experiment, it’s necessary to have measuring instruments set up around the collision point. These instruments rely heavily on superconducting magnets, which are essential for the experiment to be successful.
The superconducting magnet developed for the Topaz experiment is unique because it seeks to achieve a “transparent magnetic field.” “Transparent” means that the magnet provides a strong magnetic field while minimizing its material and thickness to the absolute minimum. By doing so, unwanted reactions are minimized, and the particle observation performance is enhanced.
The ultimate goal is to create a magnet where nothing exists but a magnetic field. Prof. Yamamoto’s achievement has brought us one step closer to realizing this goal.
Prof. Yamamoto’s extensive experience in this field spans over 30 years and has resulted in some groundbreaking contributions to our field. One of his most notable achievements was his involvement in developing superconducting magnets for the LHC accelerator beam focusing and the ATLAS experiment. This was a significant contribution from Japan to CERN.
“As I continued my research, I became very honor with my role in supporting particle physics experiments by providing the ‘field’ for them. And I have come to believe that ‘supporting’ is a wonderful thing to do.”
The development of superconducting magnet technology in accelerator experiments was applied to an experiment to observe cosmic rays using a measuring instrument mounted on a scientific balloon over Antarctica (BESS). With the incorporation of an ultra-lightweight, materially “transparent magnet” using superconductivity and persistent current technology at a central observation device, the scientific balloon flight and observation experiment orbiting the South Pole over Antarctica became a reality.
“This research project was one of the most fantastic adventures in my life. I was responsible for leading the scientific observation group for the first time in this experiment. I accomplished this through the wonderful cooperation with young and talented researchers and students. As the project leader in the extreme natural environment, I realized how grateful I was to be supported and how wonderful to support others simultaneously in this experience.”

In 2007, Prof. Yamamoto was appointed as a Project Manager of the International Linear Collider (ILC) Global Design Effort. He led the research and development of the superconducting RF accelerating cavity technology, an essential component of a linear accelerator, through international collaboration. He said, “The superconducting RF technology was very different from the superconducting magnets I had been working on before, but we still shared the same goal of providing the ‘field.’ In our efforts to develop superconducting magnet and RF technology, we took common advantage of our experience through international cooperation and collaboration with research institutes and industries. I think that the creation of “fields” such as electric and magnetic fields is destined to be taken for granted and almost forgotten once accelerators start working. They are like air, so to speak. But they are indispensable. It would be a great success if everyone could forget about our work. We can be very proud of this behind-the-scenes role.”

To conclude, Prof. Yamamoto expressed his perspective regarding the direction of the science role in the future of Japan.

With my confidence, Japan shall clearly prioritize to globally lead “science, technology, and education.” I have been deeply impressed with CERN and the founding concept, Science for Peace, which excellently motivates to unite people with any background around the world to work together on science and technology regardless of their ideologies or beliefs. It has strongly motivated me to my research and international cooperation in this field. CERN is not only fostering to promote fundamental science but also strongly contributing to society through innovation and knowledge transfer. It shall be important for Japan’s future direction to pursue establishing an international/global research organization to be hosted in Japan, with a similar concept to CERN. I believe the ILC project will take a central role in extending the prospect and realizing “Science for Peace.”

I would like to extend my sincere thanks to everybody who has trained me and worked together, and supported particle physics. I will keep my willingness to assist everyone in the next generation to lead our future in science and contribution to society.

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