CERN Gives me a Hadron! 1


After the Second World War there was huge interest in nuclear weapons and nuclear physics around the world by militaries, governments and also large groups of physicists. Lots of money involved in projects like the Manhattan Project, the science advanced in leaps and bounds and the US was pulling in scientists from all over the world. In response, European governments got together and created CERN, what today is the European Organization for Nuclear Research. This huge multi-nation initiative proved to be quite successful in keeping Europe’s best scientists and reversing the brain-drain. Today, CERN has 20 member states, and is still not allowing any non-European nations (including its largest user, the US) from joining. This means that the US cannot provide any direct monetary aid to projects, they can only provide the personnel, experience and in-kind gifts. Surprisingly, of the approximately 2400 full-time, 1500 part-time people working for CERN, almost all are engineers. There are very few actual scientists in the entire compound! The scientists are part of the network of 10,000 users that are actually doing something with the data and are dictating the experiments that are carried out.

Of course we have all heard about the recent 5-sigma discovery of the Higgs Boson, dubbed the “God Particle”. In the introductory session of the tour they explained the Higgs Field in a rather interesting analogy. Imagine two exactly identical balls on a ramp. These two balls represent any two pieces of matter on the Earth, from protons to a donkey. Now imagine that you put a tiny bit of clear glue on the balls, but in different amounts. As they roll down the ramp they will have different speeds but to an external observer that doesn’t know about the glue it will just appear like the exact same objects have this different behavior that one cannot detect with the eye. In relation to the Higgs theory, the speed at which the balls roll down the hill represents the mass of any object on Earth, and it is the Higgs Field (the glue) which determines exactly how much mass a certain object has and how “fast” it will be able to move in space.

2/3 under France, 1/3 under Switzerland, we were constantly walking between the two countries over the campus. The main 4 experiments, ALICE, CMS, LHCb, ATLAS are based around the ring of the LHC, pretty evenly spaced apart. Offshoots like the Antimatter factory which just use the energy and particles from the LHC to perform experiements are also spaced around the ring.

Layout of experiments at CERN

Layout of experiments at CERN

The LHC produces so much energy and part of this can be harvested for a range of other uses. Definitely one of the coolest uses at CERN is for Anti-matter creation. This proton beam comes into the “Antimatter factory” and is used to turn the energy into a negative electron and a positive positron (anti-electron). This pair is immediately split by powerful magnets and the stream of positrons is captured in one of the outer loops. At one time they can create about 10^7 positrons, the greatest single antimatter source on the Earth. These particles are slowed down from 3m/s below than the of the speed of light to 3metres per hour. These anti-matter particles are levitated in a vacuum for analysis. Unfortunately because the vacuum is not perfect (there will always be tiny particles left in the vacuum), the parts annihilate and the mixture can only last about 20 minutes at most.

But that’s not even the coolest thing that they do with the anti-matter! The same LHC energy is used to create another 10^7 antiprotons. Combining these with the positrons, the scientists create a completely whole anti-hydrogen (opposite of electron-proton pair). This is a completely stable (except for the annihilation part) anti-atom!! One of the tests they are performing is the classic Galileo-drops-things-from-the-Leaning-Tower-of-Pisa-Experiment. They are letting the anti-hydrogen fall down a shoot and comparing this to normal hydrogen in order to determine if gravity has any different effects on anti-particles. Unfortunately no such differences have been detected so far.

Uh oh?

Uh oh?

And then we saw a huge burst of steam come out of the anti-matter loop…whoops? Our experimental physicist tour guide assured us that that was nothing to be afraid of but then rushed us out of the building quite quickly…

Other Facts & Observations:

  • At max power the collision of particles in the LHC is 7TeV, about 1.2 mJ, which is roughly the energy that a mosquito has (so no real worries about Black Holes forming haha)
    • That being said the particles are never fired one-at-a-time, they are always in bunches of millions of particles
  • To get up the top speeds (0.999999991c) the particles are first accelerated outside of the LHC ring by linear accelerators
  • The first and only man to die as a result of the LHC project was a technician named José Pereira Lages who had a switchgear fall on him during construction in 2005
  • Collision data is in the order of tens of petabytes ever year
  • Energy consumption of CERN for a full year of operation is about 1000GWh, roughly 10% of the entire canton of Geneva
  • There are over 1600 superconducting magnets in the entire facility
  • It takes approximately 6-7 weeks to evacuate the entire LHC and start tests after  maintenance or shut down

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One thought on “CERN Gives me a Hadron!

  • opa

    Alex, once again agreat job with these two blogs. Always a great read, although I don’t understand this “thing” in cern!! In any case good luck, looking forward to your next blog. Opa