SCIENCE

Scientists at the Large Hadron Collider successfully turned it back on after two years of downtime. Proton beams will be accelerated, magnets will keep them on track, and the temperature will sink to almost-absolute zero. And then the fun will start. (Forbes)

Use our resources to learn a little about the “biggest science experiment in the world.”

Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit.

Discussion Ideas

• The Large Hadron Collider is a particle accelerator. What particles are being accelerated?
  • Protons, although CERN will remind you that they are not the only particles accelerated in the LHC. Lead ions are, too.

 

• What are protons?
  • Protons are positively charged particles that can exist on their own (freely) or as part of the nucleus of an atom. Protons are a type of hadron, the particle that gives the LHC its name.
  • According to CERN, “The proton source is a simple bottle of hydrogen gas. An electric field is used to strip hydrogen atoms of their electrons to yield protons.”

 

• According to the Forbes article, the LHC will accelerate protons from 450 GeV to 13 TeV. What do these measurements mean?
  • eV stands for “electronvolt,” a unit of energy or mass often used in particle physics. An electronvolt is the amount of energy an electron gains or loses after being accelerated by 1 volt of electricity.
  • G and T stand for the metric prefixes giga- (indicating a million) and tetra- (indicating a billion). So, over the course of the next six or so months, acceleration at the LHC will go from 450 million electronvolts (450 GeV) to a whopping 13 billion electronvolts (13 TeV).
    • To put this in perspective, according to CERN, 1 TeV is about the energy of motion of a flying mosquito . . . so the LHC will be powered by the energy of 13 billion flying mosquitoes?

 

• According to Forbes, the LHC has had improvements to its cryogenic and vacuum systems. What is cryogenics? What is a vacuum?
  • According to CERN, “Cryogenics is the branch of physics that deals with the production and effects of very low temperatures.” (Very low—close to absolute zero!)
  • A vacuum in space is lacking in all matter—no molecules, no atoms, no subatomic particles. Nothing.

 

• According to Forbes, the LHC will be able to fire proton beams in bunches—“bunches” is a technical term, by the way—separated by 25 ms. What is an ms?
  • ms stands for millisecond, one thousandth of a second. The blink of an eye is about 100 ms. (Those bunches are being fired very quickly.)

 

• How are protons accelerated in the LHC?
  • Accelerators speed them up: According to CERN, “The accelerator complex . . . is a succession of machines that accelerate particles to increasingly higher energies. Each machine boosts the energy of a beam of particles, before injecting the beam into the next machine in the sequence.”
  • Magnets keep them on track. According to CERN, “Without any other force involved, the particles would drift apart and their momentum would carry them in a straight line. More than 50 types of magnets are needed to send them along complex paths without their losing speed.”

 

• Why are the physicists forcing the particles to collide? Why not simply observe them as they collide in nature? Do “particle accelerators” even exist in nature? Read our short article on the LHC for some help.
  • Yes, particle accelerators exist in the cosmos. According to NOVA, “the universe has many naturally-occurring particle accelerators that are far more powerful than the LHC, exceeding even anything we could build in the foreseeable future. Anything exotic we can create in our labs, the cosmos has beaten us to it.” Cosmic particle accelerators can be found “near black holes or neutron stars, during supernova explosions and in the hot remnants those explosions leave behind.”
  • Well, physicists do observe particle collisions in the cosmos, as much as they can. Some of the most interesting collisions take place high in Earth’s atmosphere, where even the most sophisticated equipment can’t catalog them directly.
  • We experiment with collisions because cosmic collisions are so rare and hard-to-catch. “While astronomical sources may be good accelerators, that doesn’t mean the cosmos is full of good colliders. Our Earth-bound experiments are designed to focus beams of protons or other particles into tight ‘bunches’ . . . then send those bunches slamming into each other from opposite directions. That sort of thing is rare in space.”
    • How rare? According to CERN, even in the controlled environment of the LHC, “The particles are so tiny that the task of making them collide is akin to firing two needles 10 kilometers apart with such precision that they meet halfway.”

 

• The Forbes article says scientists at CERN and physicists around the world will be looking for new particles. What are some examples of these exotic subatomic particles?

 

TEACHERS’ TOOLKIT

Forbes: The Large Hadron Collider Is Back In Action

Nat Geo: ‘Biggest Science Experiment in the World’ Starts Up

Compact Muon Solenoid Experiment at CERN’s LHC: Glossary

LHC Portal: Glossary

CERN: Engineering

NOVA: The Astronomical Particle Colliders That Put Our Own to Shame