Are Cosmic Rays Impacting the LHC Measurements Beyond Muons?

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Discussion Overview

The discussion revolves around the impact of cosmic rays on measurements at the Large Hadron Collider (LHC), specifically questioning whether particles other than muons contribute to background noise in the detectors. The scope includes theoretical considerations and technical aspects of detector sensitivity and particle interactions.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether cosmic rays affect LHC measurements only through muons or if other particles contribute as well, and why muons are considered background while electrons are not.
  • Another participant argues that cosmic ray muons should not significantly impact LHC measurements due to the detectors' sensitivity to direction and time of arrival, although they acknowledge that cosmic rays were used to test detector efficiency before full operation.
  • A third participant notes that cosmic muons are less frequent compared to muons produced in LHC collisions and explains that cosmic muons travel in random directions, while LHC muons originate from a small interaction region. They also clarify that neutrinos can reach the detectors but do not pose a significant issue due to their low interaction probability.
  • This participant further explains that muons are a background because they are heavier than electrons and lose less energy in matter, and they mention that pion decays in the atmosphere primarily produce muons.

Areas of Agreement / Disagreement

Participants express varying views on the significance of cosmic rays in LHC measurements, particularly regarding the role of muons versus electrons. There is no consensus on the extent of the impact of cosmic rays beyond muons.

Contextual Notes

Participants discuss the limitations of cosmic muons in terms of their random directionality and the specific conditions under which they may be useful for detector alignment, but do not resolve the broader implications for measurement accuracy.

JoePhysicsNut
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I've heard of cosmic rays affecting measurements made at the LHC in the context of muons. Is it just muons that can reach the detectors or is there background from other particles as well? Why are muons a background but not electrons? How significant is it?

Thanks.
 
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Muons have a longer range than electrons, however I don't see how cosmic ray muons could be responsible for a significant background in the LHC, since the detectors by design are very sensitive to direction and time of arrival.

However there was a period before the LHC was fully operational in which data from cosmic rays was used to test the detectors efficiency.
 
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The rate of cosmic muons is low compared to the rate of muons from the collisions, and muons produced in the LHC mainly come from the small interaction region, while cosmic muons travel in random directions.

Why are muons a background but not electrons?
Muons are heavier than electrons, so they lose less energy in matter. In addition, pion decays in the upper atmosphere mainly produce muons, not electrons.
Is it just muons that can reach the detectors
Well, neutrinos can reach them, too, but they are not an issue as their reaction probability is so tiny.Cosmic muons are nice to align the detector elements before the first collisions are available - they go in a straight line, and you can see which detector elements are hit and find out where they are based on that.
 
Thanks to you both!
 

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