May 27

The US particle physics sciences thank the contributions of Felicia, a ferret who helps clean the accelerator


The size is small but the contribution is huge!

In February 1971, physicists working at the National Accelerator Laboratory located in Illinois, USA, were beginning to test the largest machine in the world at that time: an accelerator. The proton synchrotron has a circular shape with a capacity of 200 billion electro volts (billion electro vol – BeV, a unit of measurement for the energy level of subatomic particles).

Project manager Bob Wilson promised the US Department of Energy that he could put the machine into operation within 5 years with a capital of 250 million USD, and the time to start the machine for the first time was 4 years after his promise. Wilson. They immediately encountered a problem: the magnet, the essential part of the machine, was constantly malfunctioning. Failing to apply high technology to repair the machine, the team found a “low-tech” method: a ferret named Felicia.

At that time, the National Accelerator Laboratory (which is now known as Fermilab) possessed a series of particle accelerators: a linear accelerator (linac), an accelerator, a repeating loop. mechanism and a main launch ring. The linac device provides the proton beam and energy input to carry out research, the accelerator accelerates the jet, the recycling ring gathers the protons into a powerful beam, and the ejection ring accelerates the proton beam. near the speed of light.

Particles will fly over a series of research facilities, and will be bumped into each other or on existing targets. A particle detector will observe the collision, see what the particle will break up into, and whether new particles will form after the collision. All the debris that comes out from the particle-acceleration test is the fundamental building block of the Universe. The ring device, up to 6.4 km in length, is surrounded by magnets, capable of navigating and condensing the jet inside the accelerator.

Each magnet is up to 6 meters long and weighs up to 13 tons. During the initial preparation sessions, only two magnets malfunctioned due to a damaged copper coil coating. Gradually, the failure rate of 2 units/day brought the experiment to a halt, and the team had to replace a total of 350 magnets in all.

Yet on June 30, 1971, they also successfully sent the first ray: it completed one revolution around the accelerator. By August of the same year, they were able to send the beam around the accelerator 10,000 times. But when trying to push the particle to a threshold above 7 BeV, the magnet malfunctioned again.

Finally, the team realized the problem: pieces of metal scattered in the tube would float when the magnet was active, and these debris blocked the path of the particle beam. So how to scan all the scrap metal now?

Robert Sheldon, a British engineer who came to the National Accelerator Laboratory to find “a quick and economical solution”, suggested the team use a ferret mounted on his device. cleaned. When it goes through the pipe, the metal debris will follow the ferret out.

Felicia, a female ferret from a ranch in Gaylord, Minnesota, 38 cm long is the smallest individual weasel has in its possession. The team at NAL bought Felicia for $35.

They put a special collar around the ferret’s neck and clothed it in diapers, because weasel droppings can also block the path of the particle rays. On Felicia’s necklace was a long cord, one end with a cleaning item; Scientists plan to drive Felicia through a dark tunnel up to 6.4 km long. The ferret refused to work, perhaps out of fear of the long road ahead.

So the scientists decided to give Felicia an “apprenticeship” before undertaking the big project. First, they ran the ferret through a 91-meter-long tube that would later be fitted with a particle accelerator. Felicia finished the long way, although exhausted, but all 7 tasks to clean the pipe were successful: but the debris in the pipe followed the ferret out. When the public learned of Felicia’s successes in cleaning experimental metal tubes, they expressed their desire to find her a worthy husband. However, scientists say that if Felicia becomes pregnant, she will lose her job because she can no longer fit through the tube.

Meanwhile, engineer Hans Kautzky collaborating on the project has created a device called a “magnetic ferret” to deal with metal debris lodged in the tubes of a large particle accelerator. He connected more than a dozen plastic discs to a steel pole, attached to a 700-meter stainless steel cable – about the same length as a Felicia necktie, with one end attached to a permanent magnet. Using compressed air, Hans Kautzky launched “magnetic ferrets” along the accelerator’s tube and obtained very satisfactory results.

“With 12 shots, I ran the device to its full length. This can clean the pipe pretty well, although it’s not perfect.” At least, engineer Kautzky’s efforts were enough for the researchers to continue experimenting with the accelerator, and then hit the 200 BeV goal.

Felicia is retired. And when the ferret became ill, people thought of stuffed it and put it in a museum, as a way to preserve the merits of the beautiful little animal. However, after Felicia died on May 9, 1972, there is no record that the mink was stuffed. Some people have tried to contact scientists who worked on the particle accelerator project, but many people are no longer on this earth, no one knows what happened after Felicia died.

But while no one knows what happened to the ferret, Felicia’s contributions to particle physics are not small. Felicia was lucky to be chosen to collaborate, and she completed all the tasks assigned, and also enjoyed a memorable retirement at a mink farm. Maybe one day we’ll find a new bead and then name it Felicia.


ferrets, particle accelerator, particle physics, physical, research

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