Teacher Blogs

Where Particles Collide Cool Things Happen
Posted 08/03/2017 04:16PM

By Dr. B., Upper School Science

July 2017

Einstein famously said, "If you can't explain it simply, you don't understand it." I had the opportunity this month to spend a week at the nation's premier particle accelerator at Fermilab in Batavia, Illinois, before I headed out to the bigger European counterpart at CERN, Geneva, Switzerland. I'm excited to share in this blog my experience at Fermilab while also trying to explain a few basic particle physics concepts in the simplest terms with analogies. I don't want to dilute the profoundness of the actual science by using analogies but they are useful in helping to communicate phenomena.

Physicists are essentially trying to answer these two fundamental questions at Fermilab: what are the main building blocks of nature and what are their interactions? To find out the answers, the physicists collide tiny particles moving at almost the speed of light in highly sophisticated and huge machines—arguably the world's biggest—located 300 feet under ground.

Imagine two strawberries are put in a large circular chamber and given high speeds to travel in opposite directions—and then they collide head-on. Now imagine that collision creates bits and pieces of strawberries, as well as a few blueberries, acorns, grapes and even a watermelon. Sounds weird, right?

This is what makes particle physics experiments so interesting and full of mystery. Mother nature seems to play by different set of rules when size and mass get ridiculously small. A hydrogen atom for example is about a quarter of a billionth of the size of a golf ball and its nucleus is like the size of a mosquito on the field at a football stadium. Even smaller particles called quarks, leptons and bosons add on to the puzzle the physicists are trying to solve. On the atomic level at almost the speed of light, mass and energy become interchangeable. Hence, two fast particles can collide and produce more massive particles.

Scientists at Fermilab guide the products of these high-energy head-on collisions of particles (such as two protons) through many layers of a variety of detectors and analyze the data. The amount of data gathered by 40 million head-on collisions every second of two beams loaded with 100 billion protons produce thousands of "debris" particles. The role of the detectors is like a mixture of mulch, iron nails and salty water in a jar. To separate the contents of this mixture, you could use a magnet to pick up the nails, use a colander for the mulch and boil the water to evaporate the water to leave salt behind. It would be intuitive to realize that the order of these events would matter in your quest to separate the contents of this mixture.

How much data is gathered in these particle collisions? Imagine every person in the U.S. taking a picture every second for 10 hours every day with their cell phones and you are tasked to analyze these pictures for patterns and irregularities according to certain criteria. The data gathered in the particle accelerator labs are processed in huge "computer farms" and require incredible amounts of power. For example, CERN's yearly electric bill is $65 million. Most of the power is needed to guide the particles through the chambers via super conducting magnets that are 100,000 times more powerful than Earth's magnetic field through extremely cold temperatures (-400o F) and to run the super computers.

Overall, it was an incredible experience at a prestigious facility that opened up my eyes to the amazing world of particle physics. The level of science that is being conducted at this national laboratory is shaping the way we view the universe.

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