A dome building at CERN lit up against a dark blue morning sky

When Particles Collide: Visiting CERN

There is a 27-kilometer (17-mile) tunnel 175 meters (574 feet) underground on the border of France and Switzerland at the CERN (The European Organization for Nuclear Research) research facility. Inside this tube is the world’s largest high-energy particle collider the Large Hadron Collider (LHC). Physicists shoot protons through this tube at the highest possible speeds, near the speed of light, and then make them crash together to see what will happen.

The public is welcome on a first come first serve basis to explore the exhibits of this massive research center. Guests may also join a tour that gives visitors a view into the Atlas research center and entrance into the older and smaller collider that is no longer used. See the proposed schedule to make the most of your time during a visit to LHC.

The process of breaking apart atoms produces radiation so the old collider was closed to the public for 10 years after it was decommissioned. This time gap allowed the radiation to dissipate. According to our guide, the Guiger counter no longer registers radiation in the blue room containing the massive magnets and decommissioned collider tube in which we stood.

The copper linear accelerator where protons are shot through tubing that extends longer and longer.
This is a linear accelerator. After electrons are stripped from Hydrogen atoms the remaining protons enter this accelerator. Here they begin their speedy journey into the Hadron Collider.

Why is it so big?

Accelerated particles tend toward a straight line. If particles are studied as they accelerate through a straight line there are limited opportunities to study collisions along that line. However, if those particles are forced to curve and travel continuously around a circle acceleration can increase as well as opportunities to force collisions that can be studied.

First, we must get them to curve and that takes super powerful magnets. Dipole magnets are cooled to ‑271.3°C, colder than outer space and only 2 degrees above absolute zero. There are 1,232 of these dipole magnets each 15 meters long. Together they generate an 8.3 tesla (SI unit of magnetic flux density, not a car) magnetic field. This field is “100,000 times more powerful than the Earth’s magnetic field.” – numbers from CERN

These supercooled dipole magnets are used to bend the path of the accelerated protons. Even with the size and strength their influence is minuscule. Therefore it takes 27 kilometers of the world’s most powerful magnets to bend these protons into a circular path.

Three photos: Trin standing by gauges in the control room of the old collider; a signs warning of radioactivity; The massive magnets and tubing of the old collider.
On the tour, we entered the old decommissioned collider. They told us that it was no longer radioactive.

What are they looking for?

Physicists are looking for the same thing as all scientists look for, new discoveries. They are looking for answers to the fundamental open questions in physics. They study particles to understand how the universe works and holds together. Many are looking for answers to explain how the universe formed. They are looking for dark matter and the boson field, but also hoping to find new things not thought of yet.

We know that the amount of matter and energy in the universe is constant. Neither energy nor matter can be destroyed but they can be converted. Einsteins E-mc2 is a formula that reflects the relationship between energy and matter. Energy is equal to mass times the speed of light squared.

While sitting around a campfire, watching matter (logs) turn into energy (heat and light) is mesmerizing. Physicists at the Hadron Collider watch as protons are shot around the circle close to the speed of light. There are four junctions where the beams of speeding protons are bent to collide. The collation is opposite that of a campfire. Instead of matter turning to energy, the energy of these speeding protons is turned to mass. The results are just as mesmerizing to physicists as a campfire is to the rest of us. Millions of high-speed cameras and detectors record every nuance of these collisions to see if they can find evidence of the illusive invisible Higgs field.

Screenshot from the CERN tour. Only 5% of the universe is visible to us. The rest is dark energy 68% and dark matter 27%
Only 5% of the universe is visible to us, the rest is dark energy 68% and dark matter 27%

The God Particle

The Higgs field is a theorized energy field thought to be present throughout the entire universe. The Higgs Boson is the particle that interacts with this energy field and theoretically gives everything mass and holds our universe together.

Nobel Prize-winning Leon M. Lederman referred to the Higgs Boson as “The God Particle” in his 1993 popular science book entitled The God Particle: If the Universe Is the Answer, What Is the Question? ² It became a popular term to use when referring to the Higgs Boson. One of the reasons he used this term was because he likened it to the story of Babel in ancient text. Humankind built a town to create unity and reach the heavens. Lederman likens this to humans building the collider to find the particle that holds it all together and unlock the mysteries of the heavens.

After this book was published the term, “The God Particle” was widely used by the media.

Maybe some keep the name because it reminds them of other references in the same ancient book:

Colossians 1:16-17 “For in him [God] all things were created: things in heaven and on earth, visible and invisible, … He is before all things, and in him, all things hold together.” NIV

Trin looking at a particle detector for the Hadron Collider
The extremely delicate particle detector for the LHC

Discovery is the Aim

On July 4th, 2012 it was announced that both the Atlas and CMS detectors at LCH recorded a new particle. Physicists suspected it was the Higgs Boson, the particle that cannot be seen since it does not reflect light but interacts with the Higgs field to give matter mass.

One exhibit during our tour shows the newsreels worldwide that announced the discovery. They also included a few moments of the announcement itself to the scientific community. A few graphs with a blip on them are flashed onto the screen that were used during the announcement. There is excitement and tears of joy.

No other information about the discovery itself is provided during the tour or in the exhibits. The discovery matched the theory of the Higgs Boson proposed in 1964. No other resulting discoveries from finding this particle were highlighted in the multiple exhibits.

The Atlas Control Room filled with monitors and large screen projectors. One physicist sits at his desk.
During the tour, we were able to view the ATLAS Control Room through a plate glass window. The desk closest to the window had a sign that said, “Please, do not tap on the glass! It scares physicists! …however, feeding is welcome!”

What it Costs

The total expense for the CERN facility in 2022 exceeded 1.2 billion Swiss Franc ($1.4 billion). Personnel costs were almost 700 MCHF (million Swiss Franc) to pay for the staff of 2,658. Materials exceeded 215 MCHF. The cost of energy and water was 47.8 MCHF. (All data from the CernAnnual Report 2022).

The exhibits and tour are free to the public, but only available on a first come first serve basis.

A large blue conduit runs through this mock up of the 27 kilometer tunnel of the LHC. A physicist is projected on the wall and tells about this area of the collider.
This exhibit displays a section of the 27-kilometer tunnel of the LHC. A physicist is projected on the wall to tell visitors about this area of the collider.

Tips on visiting

The visitor center opens at 8 AM. To participate in a tour one must sign up on their app which is only available at the visitor center. Spots for the tour are on a first come first serve basis. To ensure we got a spot we showed up at 7:45 AM and waited outside the doors for them to open. This was unnecessary.

The app lists the exhibits and the available tour times. The first tour is at 10:30 AM and only accepts registration two hours before the start time. We couldn’t do anything then till 8:30 AM. Exhibits don’t open till 9 AM.

Tours are both inside and outdoors. Be sure to bring an appropriate jacket or umbrella depending on the weather.

List of exhibitions and tours times available at CERN
Above is the list of exhibitions and tour times available on the CERN app that is only accessible while at CERN.
WARNING: This is the schedule on the day we went – it could be subject to change.

If you want to see everything

  1. Arrive at 10:15 AM and sign up for the day pass. It will be valid for three days.
  2. Spend 45 minutes in the Discover CERN exhibit. It is the best one to prepare you for the tour and give the most information about the collider itself.
  3. Just before 11 AM head over to the auditorium to watch the Proton Express science show that starts at 11 AM.
  4. At 11:30 AM, halfway through the show, sign up for the 1:30 PM guided tour (you can only sign up two hours before the start time). If you take the earlier tour you will miss the Proton Express show. You can sign up right from your seat in the auditorium.
  5. After the show go to the restroom and get a quick bite to eat. A simple sandwich from the cafe is around $22. We took a packed lunch instead.
  6. Show up at the desk at 1:20 PM to pick up your badge for your tour and then follow your guide for the next 1.5 hours.
  7. After the tour browse through the rest of the exhibits. The best exhibit is the Discover CERN wing, which if you followed this list you saw at the beginning. If you only have time for one that is the one I suggest.
Light exhibit at LHC
An artistic display in an exhibit at CERN. It contains many moving blue pieces, believe it or not.

1 thought on “When Particles Collide: Visiting CERN”

  1. This website page is unbelievable. The brilliant substance reveals the essayist’s interest. I’m awestruck and anticipate further such mind blowing entries.

Please share your thoughts below

Scroll to Top