• Question: What kind of data do you get from the LHC?

    Asked by anon-201342 to Sophia, Sarah, Meirin on 13 Mar 2019.
    • Photo: Meirin Oan Evans

      Meirin Oan Evans answered on 13 Mar 2019:

      The data we get from the LHC is information about the particles that get created in the high energy collisions, information on particle properties such as particle energy, speed, mass and charge.
      Imagine each collision is a suitcase. We then look inside a suitcase to see the clothing items, each different clothing item being a different particle, for example an electron is a left foot sock. We then look at the properties of each different clothing item such as colour, size and material.
      What we’re most interested in finding is very rare particles (very rare pieces of clothing), such as the Higgs boson. The problem with rare particles is that they don’t live long. For example a Higgs boson only lasts for 0.0000000000000000000001s (22 zeroes!). So we don’t see a Higgs boson in our detectors, we only see the particles it breaks into. Imagine a Higgs boson was a Gucci jacket that got torn apart. We might find 2 sleeves of the same size, a collar and main body of the same colour and material. If these pieces fit together, we might conclude there was once a Higgs boson!

    • Photo: Sophia Pells

      Sophia Pells answered on 14 Mar 2019:

      I don’t work with the LHC itself. I work as part of another facility at CERN called MEDICIS. It’s a new one which uses a high energy beam of protons to produce radioactive isotopes for medical research.

    • Photo: Sarah O'Sullivan

      Sarah O'Sullivan answered on 14 Mar 2019:

      I get none, unfortunately I don’t have any links to CERN, although that would be cool it’s not quite my field of research

Comments

  • Photo: Andy

    Andy commented on :

    We get a huge (HUGE!) amount of data out of the machine… not so much the LHC itself, but the ATLAS, CMS, and other “detectors” that are built around the places that the beams collide. The detectors are built from materials that react when particles of various kinds pass through them — we try to design these to give an unbiased picture if possible. They spit out 100 million electronic signals, 40 million times a second… ridiculous! We can’t store all that data, so we have “trigger” systems that are designed to throw away the 99%+ that isn’t super-interesting to us. What remains is still a lot of data. We then run lots of computer algorithms on them to turn all the detailed info about electronic detector signals into our best guesses of what particles came from where, with what momentum, what they decayed into, etc. This is what most physicists work with. It’s still big: maybe a few thousand gigabytes for a data analysis, so we cut it down and calculate new stuff from it again and again, until it’s at a size that we can put on a laptop and make graphs from in minutes rather than weeks.

    A lot of what we do with it is the detective work of figuring out how the particles that were long-lived enough to hit the detector originated from hypothesised particles like the top quark or Higgs boson, or something totally new: we can’t see these directly since they decay so fast, so we need to infer their existence indirectly, and using a lot of statistics methods… and these days lots of Artificial Intelligence ideas (I’m writing this from a conference on stats and AI in physics!).