Issue 76

Beam Dynamics Newsletter

2 Tribute to Yong Ho Chin

Yong Ho Chin, the Chair of the ICFA Beam Dynamics Panel, passed away quite unexpectedly early in January 2019.

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Most of the members of the Panel remember him for his quiet but firm leadership, his clear thinking, and his remarkable ability to absorb but not create controversy. He was clearly good at managing people and making them feel their efforts were appreciated. He was good company, good to talk to, intelligent and very knowledgeable, with amusing snippets of stories drawn from experiences in his past life.

His natural talent for resolving issues, always in a warm, respectful manner, spilled over into his physics. He was able to combine two different points of view into one and at the same time generalize the results of both. His technical ability was widely recognised but so too was his generosity of mind.

Yong Ho had been hoping to develop the activities of the Panel further, making it more pro-active in encouraging initiatives and collaborations in those areas of beam dynamics most important for future accelerator physics. It is a huge blow to us all that he was unable to achieve his vision and see through the vital role he was expecting to play.

The editor asked a selection of people to contribute their memories of Yong Ho to try to bring out the character of the man.

Swapan Chattopadhyay, who was involved with Yong Ho from the earliest days of his career, writes:

In remembering Yong-Ho, I have the singular distinction of having been in a position to have secured a permanent career position for him as a staff scientist at Berkeley Lab in my accelerator center in the 1980s. Young-Ho was at CERN at that time and it was non-trivial to secure him, as CERN kept offering him extended short-term contracts with attractive tax-free CERN-style salaries. In my negotiations and interactions with him, I was most impressed and struck by Yong-Ho’s desire to understand his scientific research portfolio in his future appointment in detail, without ever raising any questions of substance about salaries, compensations etc. He decided to join my group at Berkeley based purely on the scientific canvas that he envisioned and the relative stability/permanence of the position, allowing him to do his research unimpeded and not wowed by financial packages.

Second, after a few years at Berkeley when Yong-Ho joined KEK in Japan as a junior accelerator professor and scientist, he had an unusually keen sense of humor, being very aware of his special status as a Japanese citizen in his own right, but with also a special status as one with a Korean heritage, with all its implications as a citizen. There were many exchanges between him and our mutual mentor and colleague Dr Kimura-san and myself about the pros and cons of this status, sociologically, culturally and scientifically. Yong-Ho never focused on some of the negative aspects of this as I have heard from many others, but kept on focusing that he could serve as a scientific ambassador of collaboration with Korean and Chinese universities, laboratories and institute in matters of international and pan-Asian collaboration on Linear Collider research and design etc. – and this he did in an exemplary way later in his career for all to behold.

Third, his integrity on the face of personal tragedy is worth mentioning. When he found out and shared with me the terminal nature of illness of his intelligent and beautiful wife, whom he stood to lose in a short order of time, he continued to attend to her while burying himself unusually deep into long hours of work and research via tele-commmuting, and no one knew how intense a personal life he was living at that point in time judging by his prodigious productivity.

Yong-Ho was a quiet and substantial scientist in his research. I could get him to the point when he would drop his guard and boast about his wake-field and electromagnetic code being superior to all others etc. But he was always very polite when dealing with colleagues, though I have heard that he stood his ground when some senior scientists kept on questioning his formulation of the code in Europe, which actually had left a scar with him, eventually healed by its own merits.

We were personal friends and he introduced me to Japanese and Korean food, culture and many historical tid-bits. I will miss him dearly, professionally and personally.

  Swapan Chattopadhyay, Fermilab, USA

Weiren Chou, former chair of the ICFA Beam Dynamics Panel, writes:

Yong Ho was a long-time friend and colleague of mine. We got to know each other about 30 years ago in 1989 when I was at ANL. Yong Ho, then at LBL, came to a workshop and made an elegant presentation on a longitudinal mode-coupling instability model for bunch lengthening. This was subsequently published in the workshop proceedings ANL/APS/TM-5, April 1990.

We then began a collaboration on impedance and instability studies. An example of this work was a comparison of three impedance codes: TBCI (by Thomas Weiland), ABCI (by Yong Ho) and BPERM (a boundary perturbation method code by me). For an insertion device, the three codes gave nearly identical wakefield curves, one of a few successful examples of code benchmarking.

In 2002, Yong Ho, several colleagues and myself started a new ICFA Advanced Beam Dynamics Workshop (ABDW) series on high intensity, high brightness hadron beams (the HB series). The first three workshops in the series took place in the US (2002, Fermilab), Europe (GSI, 2004), and Asia (KEK, 2006). The 2006 workshop was chaired by Yong Ho. These workshops were well received by the community and this biennial series continues today, and the 3-continent rotation pattern has become a tradition.

In 2016, Yong Ho was appointed by ICFA to be the new Beam Dynamics Panel Chair and succeeded me in that role. The transition went smoothly and Yong Ho did an excellent job as Chair. His sudden passing was totally unexpected and a shock to me.

Yong Ho was an excellent accelerator physicist. His contributions will be remembered for a long time. He will be deeply missed as a friend, a colleague, and a wonderful person.

  Weiren Chou, Fermilab, USA

Yoshishige Yamazaki, formerly of KEK, now at FRIB, gives his thoughts on “Missing Yong Ho”:

At the news that he passed away, I was so embarrassed and shocked, since I had lunch together with him last November. He looked so healthy and strong. He himself proposed and planned the special lunch to celebrate that our common KEK supervisor, Prof. Koji Takata, had been awarded a very honorable medal from the Japanese government for his great accomplishments on RF technologies. Yong-Ho scheduled the lunch that prompted my visit to Japan. He also encouraged me very much, since I was so depressed that my wife got sick, and I paid the visit to discuss with a doctor on my wife’s case.

Then, early January he would have come to Michigan to serve as a scientific program coordination committee member for NAPAC 2019, that I am chairing. He has been always a great help to me for this kind of occasion.

When I first met him, he was just 22 or 23 years old, a young boy, very good looking, and of course, very smart. He was a master course student of the University of Tokyo and staying at KEK in order to work on accelerator physics. At that time, I was fabricating accelerating RF cavities on my design for the KEK Photon Factory. I was also investigating possible coupled bunch instabilities by these cavities both theoretically and empirically. He came to my office, and asked me several questions on modes in cavities. I explained these, showing my own note book. I made this note book for my own purpose, summarizing all possible modes and their longitudinal or transverse impedances in a pill box cavity, including the relations to the growth rates of the coupled bunch instabilities. After he became a world expert on this field it has been my great pride that he learned these physics at first using my note book.

Ever after, he was one of my best friends, and helped me both technically and privately. Beam instabilities and related problems at the J-PARC accelerators was his responsibility. On my request, he chaired HB2006 held for the first time in Japan, and was SPC chair of Linac 2010. He had a very good sense of coordination of international affairs. Thus, he gave me many good suggestions and advice whenever I was organizing international conferences and collaborations. I believe that this is not only for me, but for many people. His passing away is thus a really great loss to our world-wide accelerator community.

  Yoshishige Yamazaki, Facility for Rare Isotope Beams (FRIB), Michigan USA

The next edition of the Newsletter will contain articles highlighting Yong Ho Chin’s work and scientific achievements.