A Hyakumeizan encounter with the father of modern physics in Japan
The Japanese will never cease from putting shrines on their favourite mountains and Shari-dake was so honoured in 1935. Its summit sanctuary is sacred to Ōyamatsumi-ōkami and Ame-no-mikumari-ōkami. In 1936, Dr Nishina Yoshio, who had come to the mountain to take measurements of cosmic rays during the solar eclipse that year, dedicated a torii gate of silver birch wood…
The word “organisation” gives an impression of formality, but the whole Laboratory was really a very easygoing, free and friendly group. We related to each other as equals, except in research, and the senior members were kind and solicitous towards newcomers like me. I felt then that this highly supportive atmosphere, exceptional especially in those days, was a naturally occurring phenomenon. However, in hindsight, I realise that it was probably a reflection of Dr. Nishina’s personal ambitions. I think he was eager to create the kind of atmosphere that he had experienced during his eight-year stay in Europe, in the circle of highly talented men who followed and revered Professor Niels Bohr…
Ernest Lawrence had devised a few years earlier at Berkeley. With advice from Lawrence – who remained a life-long friend – construction of a small cyclotron started in 1936.
Meanwhile, Nishina had also started to take an interest in cosmic rays, as a source of sub-atomic particles with energies that no cyclotron could match. A cosmic ray research group was set up in 1931-32. This was a lively epoch in an emerging field of enquiry.
When a foreign group reported that some particles, perhaps neutrinos, were capable of penetrating deep underground, Nishina said “Interesting, let’s try it” – a characteristic phrase – and his group took their detectors to the innermost reaches of the Shimizu tunnel. Cosmic ray experiments were also installed on the roof of Riken, on an ocean liner, and atop Mt Fuji – transforming Japan’s most eminent Meizan, not for the first time, into a mountain of science.
Others who stayed at the mountain's foot, including a British delegation were not so lucky; low clouds obscured their view. In the event, the needles of Nishina's apparatus barely wavered during the eclipse, confirming that cosmic rays originate from far beyond the solar system.
By January 1944, the Army's "N-Project" (N stood for Nishina, not for nuclear) had produced a rice-sized crystal of uranium hexafluoride. The next step would be to run a larger-scale refinement process using a thermal separator. But in March 1945, most of the Riken buildings burned to the ground after a bombing raid, effectively ending the project.
The N-Project brought down on Nishina's head a petty yet savage act of reprisal. In November 1945, a low-loader drove unannounced into what was left of the Riken compound. Soldiers started to break up the laboratory’s large cyclotron as the scientist remonstrated and his wife and secretary stood by and wept. Then the wreckage was dumped in the sea (below).
Fortunately, Nishina was able to ally himself with American physicists such as Karl Compton, the president of MIT, to prevent Riken itself sharing the cyclotron’s fate. During the first desperate post-war years, he also oversaw a project to manufacture penicillin, as way of shoring up the institution’s finances.
Once Riken’s future was safe, Nishina prepared to return to physics research. But this was not to be. His colleagues were planning his 60th birthday party when he suddenly fell ill. The celebration had to be cancelled and he passed away on January 10, 1951.
Sixty years later, Riken continues to flourish as one of Japan’s leading centres of fundamental research. Cosmic rays are still a speciality. Recently, Riken scientists used them to illuminate the inner structure of Mt Asama, a volcano and yet another of the Hyakumeizan. One can almost hear Nishina-sensei murmuring his encouragement, “Mmm, interesting, let us try it …”
Nihon Hyakumeizan in the forthcoming translation as One Hundred Mountains of Japan
Dong-Won Kim: Yoshio Nishina: Father of Modern Physics in Japan
Thomas C. Reed, Danny B. Stillman: The Nuclear Express: A Political History of the Bomb and Its Proliferation
Many thanks to sunnybeauty, threepinner and tsubame for allowing me to link to their photos on flickr.