In December 2014, the European Organization for Nuclear Research (CERN) announced that the Large Hadron Collider (LHC) is being prepared to start running again in March 2015 for the next three years. This is very exciting news in the field of particle physics, because half of the world’s particle physicists go to CERN to conduct their research.
The LHC is the largest and most powerful particle accelerator in the world. In other words LHC is physics paradise. It is a 27 km ring, made of superconducting magnets that control the particle beams inside the ring. The superconducting magnets are made from coils of superconducting material. This material needs to be cooled to extremely low temperatures using liquid helium and can conduct electricity without any losses of energy. (Indeed, superconductors could solve the energy crisis, but we don’t yet have superconductors operating at room temperature.) Inside the ring, there are two pipes, kept at an ultrahigh vacuum, in which two particle beams can move in opposite directions. The particle beams are accelerated until they reach velocities close to the velocity of light (the universe’s speed limit). Then magnets are used to focus the beams to increase the chances of collision. Finally the beams are made to collide at four locations. At each location, a different detector collects data from the collisions. The detectors are called ATLAS, CMS, ALICE and LHCb. Hadrons are the family of particles smashed in the LHC. These are particles that are composed of more fundamental particles called quarks.
All this particle smashing has provided us with a great insight into what are the building blocks of matter. One of the first major achievements was the discovery of Z and W bosons. The existence of these particles provided evidence for the electroweak theory that describes two of the four forces in the universe: electromagnetism (interaction of charged particles) and weak nuclear force (responsible for radioactive decay). The other two are gravitation (interaction of massive bodies) and strong nuclear force (responsible for binding the protons in the atomic nucleus). The understanding of these forces is at the heart of physics research and the authors of the electroweak theory received the Nobel Prize in physics in 1979.
Another important achievement was the creation, isolation and maintaining (for 15 minutes) of antihydrogen atoms. In the beginning, there were matter and antimatter particles. They collided and annihilated each other, releasing energy. In the end, some matter was left over and it now makes up you, me, the newspaper you are holding in your hands right now and everything else in the universe. Hence the creation and study of antimatter particles is an amazing achievement. In 2011, the news of particles moving faster than the speed of light shocked the physicists all around the world. This would have been a ground breaking discovery, disproving Einstein’s theory of special relativity. However, it turned out to be a false alarm. The most recent major achievement was the discovery of the Higgs boson. This particle was predicted by a theory called Brout–Englert–Higgs–Guralnik–Hagen–Kibble Mechanism proposed in the 1960’s. This theory is important because it explains how some particles gain mass. In 2013, Peter Higgs and François Baron Englert shared the Nobel Prize in physics for their work on this theory. All the scientific discoveries are wonderful, but are these experiments safe?
In the future it may be that the most powerful accelerators may produce black holes. Such an event is predicted by the superstring theory. Superstring theory is a model that unifies the four forces and the particles in the universe by modelling them as vibrations of extremely tiny strings. Superstring theory is considered ‘hardly science’ to some physicists. To others it is a promising candidate for the ‘theory of everything’. So what if a black hole is produced? Will we all get ripped into molecules? In the November Issue of Trinity News, I wrote about Hawking Radiation. Hawking’s theory predicts that the small black hole produced in the collision would evaporate very quickly by emission of Hawking radiation.
I hope that you are convinced about all the wonderful science that comes out of the LHC. However, particle accelerators also have many important applications outside of the realm of particle physics. Particle accelerators are widely used in industry, research and medicine. In industry, particle accelerators are used to produce shrink wrap for food items, DVD’s, CD’s, etc. Accelerator technology is also used in semiconductor manufacture to implant ions in silicon chips. Semiconductors are used in many electronic devices such as computers, phones, etc. In medicine, accelerators are used to produce radioisotopes for diagnostics and treatments in hospitals all around the world. Particle beams are used in treating certain kinds of cancer. Also x-ray beams are used in the pharmaceutical research to analyse protein structures accurately which leads to the development of drugs. In the future, particle accelerators could be used to treat nuclear waste. All of these applications have a strong impact on our lives and I’m not sure how we can live without particle accelerators.
At the beginning of last year, a group of Trinity students launched a campaign “to promote the benefits of CERN membership to Ireland”. Member states give financial support and have special privileges. It is quite hard to believe that a developed country like Ireland, still isn’t a CERN member state. Hopefully, this will soon change.
The research at CERN addresses some of the most difficult questions about the universe. The accelerator allows us to probe the universe to uncover its fundamental structure. I look forward to the research that will take place at CERN in the next three years. I hope the world will learn some new interesting physics and that Ireland will soon join other European countries in becoming a CERN member state.