What Is the Giant “D”? The Jaw-Dropping Power of the Cyclotron Accelerator at Japan’s National Museum of Nature and Science
I’m Ken Kuwako, your Science Trainer. For me, every day is an experiment!
Have you ever heard of a machine that unravels the mysteries of the universe and matter by whirling invisible particles at breakneck speeds? Its name is the “Cyclotron.” While it’s a staple in high school physics textbooks, the sheer scale of this particle accelerator is hard to grasp through text and diagrams alone. Today, I’ll share my encounter with a real cyclotron at the National Museum of Nature and Science, and introduce a fantastic digital tool that makes its inner workings surprisingly easy to understand.
Giant “Ds” That Spin Particles! The Cyclotron at the National Museum of Nature and Science
When “accelerators” come up in high school physics, the first name on the list is usually the “Cyclotron.” This device uses two “D-shaped” electrodes placed face-to-face. By masterfully balancing magnetic and electric fields, it accelerates particles like electrons into a spiral path, boosting them to incredible speeds.
During a recent visit to the National Museum of Nature and Science in Ueno, Tokyo, I came across a cyclotron that was actually used in the past. Seeing it in person, I was absolutely blown away by its massive scale!
Here is a close-up of the “D” section, the heart of the machine. You can clearly see how the two giant semicircles are fitted together.
Thinking about how those microscopic, invisible particles were racing through this massive hunk of metal gives me chills—it’s like feeling the pulse of scientific history!
Visualizing the Magic: How a Cyclotron Works
When I explain the principles of a cyclotron to my students, it’s quite a challenge to get them to visualize “circular motion” and “acceleration by an alternating current (AC) power source” happening at the same time. While searching for better teaching materials, I found a brilliant website called “High School Physics CG Animation Materials.”
Created by a high school teacher, this site perfectly recreates the complex movements of a cyclotron with CG animation. The best part is its “usability.” You can toggle the display to focus on specific steps, such as “Circular Motion Only,” “AC Power Switching,” or the “Moment of Acceleration.” When I used it in my class, the concept of “switching the electric field at just the right moment to accelerate”—which is so hard to convey with still images—became instantly intuitive. My students were captivated!
Experiencing the physical impact of the real machine makes you wonder, “Why is it shaped like this?” Then, seeing the CG animation turns that curiosity into an “Aha!” moment. If you’re currently studying physics, I highly recommend visiting the museum to feel that scale for yourself. It will make your studies feel much more real, multidimensional, and exciting!
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