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Adam Yurkewicz | USLHC | USA

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Millions of collisions this weekend?

The excitement is building again here at CERN.  The LHC team is planning to collide protons in the LHC for several hours tomorrow, and the next few days after.  The goal is to provide the experiments with their first million collisions (a few weeks ago we had only a few hundred).  We need millions of collisions just to start to calibrate the detector, and to re-discover some of the well known particles (that will be created in the collisions via E=mc^2) and prove our detectors are working correctly.  There are a few differences between the upcoming collisions and the first collisions a few weeks ago.  First, there will be more protons in the LHC (probably about 4 billion protons in each “bunch” of protons, with 4 bunches simultaneously going in each direction around the LHC).  Second, the LHC teams have been carefully studying the beams in the LHC in the last few weeks so the bunches of protons should be better packed together.  This will decrease the number of protons straying away into the beam pipe, allowing the beams to stay in the machine for hours, and leading to more collisions.

This is not a chance to discover the Higgs boson (that will probably take many years), but it will be the first time we use the whole detector together to detect a significant number of collisions.  In the next few weeks, we will collect enough data to do quite a few checks and calibrations.

CERN closes December 18 for a few weeks, and we won’t have beams back in the LHC until at least February.  While we wait, we will analyze the data collected in the next few weeks.  Then the LHC will ramp up the energy of the beams and we will have billions and billions of collisions through the rest of 2010.


9 Responses to “Millions of collisions this weekend?”

  1. [...] This post was mentioned on Twitter by David Parker, US LHC. US LHC said: US #LHC blog post: Millions of collisions this weekend? http://bit.ly/6y8C3A [...]

  2. Wallmott says:


    Any idea of what energy the collisions will be at?

  3. Adam Yurkewicz says:

    Hi Wallmott,
    0.9 TeV center-of-mass. Probably not too long after it will go up to 2.4 TeV.


  4. Wallmott says:

    Have they compared the LHC collisions with the Tevatron collisions at the same energy levels? If they have, is there any big difference in the results?

  5. Natasha says:

    We gonna die I’m scared an plus don’t wanna die got 3 kids I wanna see grow up

  6. Oded says:

    You’ll have Sagans of collisions! :)

  7. Matthew says:

    How does 2.4 TeV compare to a lightning strike?

  8. A 2.4TeV lightning strike would reach from CERN to Moscow. But that’s comparing apples and lemons because the energy in the LHC protons is not imparted “all in one go” like the electrical difference between clouds and ground that produces lightning is. It’s accumulated over many turns of the machine.

  9. Jonathan C says:


    According to Wikipedia


    1 TeV = 1.602×10-7 J
    “about the kinetic energy of a flying mosquito”

    The 2.4TeV is the collision energy, eg the combined energy of the two protons that are colliding, the energy per proton is half that – 1.2TeV. It’s a lot of energy to put in a space the size of an atomic nucleus, which is why the physicists are all so excited, but in our large-world terms it’s not much.

    Having said that, you wouldn’t want to put your hand in the way of the beam. To increase the chance of collisions happening they fly a couple of billion protons together in a bunch, and then you’re up to a combined figure of several hundred joules. Later they’ll fly several thousand bunches around the ring, one after the other, to increase the rate of collisions even further, but even then the total energy carried by both beams is about 700 times less than an average lightning strike (500MJ, again according to Wikipeadia), or so my calculator suggests (I’m willing be corrected by a real physicist if I’ve got this wrong!).

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