Radioisotope Day

What Is Radioisotope Day?

December 6th is "Radioisotope Day" in Japan, marking the 1890 birthday of Dr. Yoshio Nishina, known as "the father of modern physics in Japan."

Dr. Nishina and the Cyclotron

Born in Okayama Prefecture, Yoshio Nishina was a physicist who laid the foundations for nuclear and particle physics research in Japan.

• Building the cyclotron: in 1937 he completed Japan's first cyclotron (a circular particle accelerator) at the RIKEN research institute — said to be the first built outside the United States and the second in the world
• Its use: the cyclotron is also used to produce radioisotopes (radioactive isotopes)
• Mentorship: he trained many outstanding physicists and made enormous contributions to the postwar development of Japanese physics

What Exactly Is a Radioisotope?

A radioisotope is an element that emits radiation as it transforms into another atom, and it's used across a wide range of fields, including medicine (cancer treatment and diagnostic imaging), industry, and agriculture. In 1990, Japan issued a commemorative stamp marking the 50th anniversary of radioisotope use, featuring a portrait of Yoshio Nishina.

Tips for Marking This Day

• Learn about Dr. Nishina's achievements and life story
• Learn how radioisotopes are used in medical settings today
• Learn about the history of physics research in Japan, including at RIKEN
• Learn how a cyclotron or particle accelerator actually works

Invisible Radiation, Supporting Medicine and Science

The path Yoshio Nishina opened in nuclear research led directly to technologies now indispensable in cancer treatment and diagnostic imaging. Let December 6th be a day to reflect on the invisible benefits born from one physicist's passion.