Why Would You Put A Ferret In A Particle Accelerator?

She was the most adorable particle physicist ever!

Russell is a Science Writer with IFLScience and has a PhD in the History of Science, Medicine and Technology

Dr. Russell Moul

Russell is a Science Writer with IFLScience and has a PhD in the History of Science, Medicine and Technology

Dr. Russell Moul

Science Writer

Russell is a Science Writer with IFLScience and has a PhD in the History of Science, Medicine and Technology.

Science Writer

Black and white photo of a ferret exiting a tube

Felicia in action.

Image Courtesy Of Fermi National Accelerator Laboratory

In February 1971, physicists working at the National Accelerator Laboratory (NAL), Illinois, were faced with a puzzle. They were testing a new state-of-the-art machine they had built. The 200-billion-electron-volt (BeV) proton synchrotron particle accelerator was not only extremely sophisticated, but it was also the largest machine in the world at the time. To say its creation was exciting would be an understatement, and it was worth the five years and $250 million spent on building it. However, there was a problem – it kept failing. But don’t worry, the scientists knew what to do. They needed a ferret. 

A slow acceleration 

Particle accelerators are at the cutting edge of physics. They use electromagnetic fields to propel charged particles along miles-long tubes to the point that they are moving almost as fast as the speed of light. These particles then collide with others and break into subatomic particles that reveal information about the nature of matter. 


Today, we are used to hearing about the results of experiments carried out with the Large Hadron Collider at CERN, Switzerland – but back in 1971, the device at NAL (now the Fermilab) was almost 7 times more powerful than any other accelerator in the world. It could therefore push particles to energies that had never been achieved by humans before. But even after four years of construction, the accelerator was not working. 

In the space of seven months, the physicists working on the machine had replaced 350 of the 13-ton magnets that were needed to speed up the particles. Every time they excited the particles with a lot of energy, the magnets faltered and shorted out. The issue was one of contamination – during its construction, small amounts of metal had accumulated in the vacuum tubes that made up the 4-mile- (6.4-kilometer) long accelerator. Worst still, these tubes were about as wide as a tennis ball, so cleaning such a tight space was more than a challenge.   

Felicia to the rescue

The physicists were faced with a dilemma. They needed a solution that was both quick and affordable. That’s when a British engineer called Robert Sheldon had an ingenious plan – why not use a ferret? Sheldon had grown up in Yorkshire, England, where ferrets were used to flush rabbits out of their warrens, so he thought the adorable little hunter would be ideal for crawling through the tubes to clean them. 

A request was sent to the Wild Game and Fur Farm in Gaylord, Minnesota, and soon after Felicia arrived at her new place of employment. She was 38 centimeters (15 inches) with brown and black fur, with white patches on her face, and cost the team $35. 


Her work uniform included a leather harness and a makeshift diaper (to prevent metal debris from being replaced by ferret poop). She was then trained to travel through increasingly longer tunnels as she was initially reluctant to enter the accelerator. Finally, when she was ready, she scampered through tubes, pulling a piece of string with her. Once through, one end of the string was connected to a swab soaked in cleaning fluid, which the physicists then pulled through the tunnel to clean it. 

Felicia made multiple successful runs through the tubes, but eventually, she was replaced by a “magnetic ferret”, a mechanical process for cleaning the tubes. On March 1, 1972, the accelerator was clean enough to finally work and the team reached the target energy of 200 BeV. 

During her time at NAL, Felicia was treated like a princess. She was beloved by the scientists who used to feed her liver, chicken, fish heads, and raw hamburger – which was apparently her favorite. Some of the staff even took her home for the night when she could not go back to the mink farm where she lived. 

However, in May 1972, Felicia was at the home of an NAL employee when she became ill. She was taken to the vet the next day, but unfortunately, she died a few days later from a ruptured abscess in her intestinal tract. 


At the time, many of the mourning physicists wanted to have her remains stuffed so that she would forever be a representative of the early days of NAL’s existence (as well as a monument to ferret history). Despite the enthusiasm for the idea, it does not seem to have happened. And that’s okay, because regardless of whether she was preserved through taxidermy or not, the world still remembers the ferret in the accelerator. 


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  • ferret,

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  • history,

  • particle accelerator,

  • weird and wonderful