Beam Dump

05.03.10

posted by: dberry

I was on DQM online shift on Sunday and we were preparing the detector for stable beams. While this was  happening the LHC was injecting probe beams in the accelerator to verify that the LHC is functioning correctly. After they were done circulating the probe beams they are dumped into a beam stop, which is a big chunk of metal. When this happens the beam produces a huge shower of particles, most of which decay to muons. These enter the detector and make crazy looking events like the one below. The red lines are incorrectly reconstructed muons from hits in the cathode strip chambers.

Beam Dump Event

Be the first to like.
Unlike

Tags:

This entry was posted on Monday, May 3rd, 2010 at 9:51 am and is filed under CERN, Particle Physics. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

2 Responses to “Beam Dump”

  1. pmooney Says:
    May 3rd, 2010 at 10:27 am

    Hi Doug,

    Thanks for sharing this unusual “event” with us. For the benefit of your audience would you explain how you know the muons are incorrectly reconstructed and why the software makes this “mistake”. (You did say that muons were present. What’s incorrect about the reconstruction?) This would give your audience several insights into the workings of a collider detector and the associated reconstruction software.

    Alternatively you could challenge your non-particle physics portion of your audience to come up with an explanation to see what sort of discussion ensues over the next 2-3 days.

    Thanks,
    Pat

  2. dberry Says:
    May 4th, 2010 at 3:39 am

    The reconstruction algorithm assumes the muons are coming from the primary vertex, which is the yellow dot in the center. However, we know that the muons are actually coming from the right. We can tell this because there are more hits in the right side than the left side.

    The muons from the beam dump make the CSCs fire. The reconstruction algorithm looks at these hits and tries to make a centrally generated muon (Red Lines). However, these muons aren’t coming from the center, so the reconstruction is invalid.