Chris has an M.A. in history and taught university and high school history.
When was the last time you received an award? Perhaps you were recognized for completing a big project at work, or maybe you got special mention after you received the highest marks in a class. It's a great feeling.
For scientists, it would be difficult to find a bigger award than the Nobel Prize. In this lesson, we will examine the life and work of the man who received the 2015 Nobel Prize in Physics, Takaaki Kajita.
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Takaaki Kajita was born in 1959 in a small town with a long name: Higashimatsuyama, in Japan. The town was a small, rural enclave, located roughly an hour north of Tokyo. His boyhood home was surrounded by rice fields.
Kajita's high school had a less structured curriculum, which allowed the students to pursue their own areas of interest. As a result, Kajita spent a large amount of his youth studying the Japanese style of archery called Kyudo. Though Kajita was admittedly not very good at Kyudo, he continued to practice it all throughout his time in high school and in university.
After high school, Kajita was admitted to Saitama University where he began studying physics. Kajita became particularly interested in experimental particle physics, leading him to continue studying in graduate school. In April 1981, he joined Professor Masatoshi Koshiba as a graduate student at the University of Tokyo.
Soon after beginning, Kajita was asked by a fellow graduate student to begin working on the Kamiokande experiment at the Kamioka Observatory in Hida, Japan. The Kamiokande experiment was designed to detect the decay of protons. It attempted to do this by burying a large tank of pure water deep underground, which was connected to many specialized sensors that detected the radiation generated when protons decay. These type of detectors must be buried deep underground to protect them from the cosmic radiation commonly found on the Earth's surface.
Kajita's experience with the Kamiokande experiment caused him to choose a professional career in experimental physics. He wrote his doctoral dissertation on the early results of the Kamiokande experiment and received his Ph.D. from the University of Tokyo in March 1986.
Kajita did not find immediate success as a professional physicist, as he was refused a research position with the Japan Society for the Promotion of Science shortly after receiving his degree. Fortunately, his former professor was able to secure him a position at the International Center for Elementary Particle Physics.
After two years there, Kajita's experience on the Kamiokande experiment paid off. In 1988, he moved to the Institute for Cosmic Ray Research (ICRR) to work on the Kamiokande's sequel, often called the Super-Kamiokande or Kamiokande-II.
The Super-Kamiokande intended to build upon the results of the first experiment by building a much larger, more sensitive detector on the same site at the Kamioka Observatory. The project took years to design, and Kajita and his team collaborated with various groups around the world to build it. Super-Kamiokande finally opened in April 1996 after a year of underground construction work. Two years later, Kajita made arguably the biggest discovery of his career.
Kajita detected neutrinos, or very, very tiny particles which physicists believed existed but had yet to observe. However, simply observing them was not Kajita's breakthrough. The math, after all, told physicists that neutrinos must exist and that they had no mass. But, Kajita was able to observe evidence of neutrino oscillations. This means that neutrinos could shift between their three types, thus confirming that they do have mass. The discovery has caused physicists to fundamentally rethink the Standard Model, or the basic physics theory of fundamental particles and how they interact.
Kajita's work was confirmed two years later by a separate, similar experiment led by Dr. Arthur McDonald in Sudbury, Canada. For their ground-breaking work, both Kajita and McDonald received the 2015 Nobel Prize in Physics.
Kajita currently serves as the Director of Center for Cosmic Neutrinos at the ICRR and continues to lead on various underground particle physics experiments.
Takaaki Kajita is a renowned particle physicist and the 2015 Nobel Prize winner in Physics. Though Kajita's first passion was archery, he studied physics at Saitama University before joining the University of Tokyo as a graduate student. There, he worked on detecting proton decay in the first Kamiokande experiment.
In the mid-1990s, Kajita helped design and construct the successor experiment, the Super-Kamiokande. It was during this experiment that he detected neutrino oscillations, proving that neutrinos have mass and contradicting the accepted Standard Model of physics.
For the discovery, Kajita shared the 2015 Nobel Prize in Physics with Dr. Arthur McDonald of Canada.
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