Quantcast
  • Register
PhysicsOverflow is a next-generation academic platform for physicists and astronomers, including a community peer review system and a postgraduate-level discussion forum analogous to MathOverflow.

Welcome to PhysicsOverflow! PhysicsOverflow is an open platform for community peer review and graduate-level Physics discussion.

Please help promote PhysicsOverflow ads elsewhere if you like it.

News

New features!

Please do help out in categorising submissions. Submit a paper to PhysicsOverflow!

... see more

Tools for paper authors

Submit paper
Claim Paper Authorship

Tools for SE users

Search User
Reclaim SE Account
Request Account Merger
Nativise imported posts
Claim post (deleted users)
Import SE post

Users whose questions have been imported from Physics Stack Exchange, Theoretical Physics Stack Exchange, or any other Stack Exchange site are kindly requested to reclaim their account and not to register as a new user.

Public \(\beta\) tools

Report a bug with a feature
Request a new functionality
404 page design
Send feedback

Attributions

(propose a free ad)

Site Statistics

123 submissions , 104 unreviewed
3,547 questions , 1,198 unanswered
4,552 answers , 19,366 comments
1,470 users with positive rep
411 active unimported users
More ...

How to distinguish high-energetic muons and electrons in the CMS and ATLAS muon detectors?

+ 6 like - 0 dislike
81 views

At a typical energy of about 100 GeV, a muon has a Lorentz factor of about 1000, an electron about 200.000. The flight time to the detector should be around 30 ns (assuming d= 10m from the collision point). While e- would practically have the speed c, the muon's speed is about 0.9999995 c, causing a delay of about 15 fs, barely measurable I think. Is there a way to distiguihs e- from mu, unless we assume prior knowledge (that they have passed the electric calorimeter, about the penetrating power etc). Or, to put it in another way: what is the energy threshold below which they can be distinguished directly?

This post imported from StackExchange Physics at 2014-03-24 04:42 (UCT), posted by SE-user ClassicalPhysicist
asked Aug 19, 2013 in Experimental Physics by ClassicalPhysicist (30 points) [ no revision ]
I their behavior in the calorimeter is how they are distinguished because (as you noted) all ultra-relativistic particles have the same time or flight. At high enough energy it may simply be harder to distinguish them.

This post imported from StackExchange Physics at 2014-03-24 04:42 (UCT), posted by SE-user dmckee

1 Answer

+ 3 like - 0 dislike

The electron and the muon have the same charge, but the muon is 200 times heavier than the electron. The bremsstrahlung emitted by all charge particles in interactions with electric or magnetic fields depends on the mass of the particle:

In limiting cases examined the total radiation goes as at least m^- 4

which accounts for why electrons lose energy to bremsstrahlung radiation much more rapidly than heavier charged particles (e.g., muons, protons, alpha particles)

This is utilized by constructing electromagnetic calorimeters which absorb all the energy of the electrons while the same momentum muons pass through with minimum ionization losses, and also pass through the hadronic calorimeters without interacting, since they only have electromagnetic and weak interactions.

In this CMS detector slice one sees how the calorimeters perform.

cms slice

One can see the muon going through all that mass of detectors, while the electrons shower in the electromagnetic calorimeter and are contained.

This post imported from StackExchange Physics at 2014-03-24 04:42 (UCT), posted by SE-user anna v
answered Aug 20, 2013 by anna v (1,710 points) [ no revision ]

Your answer

Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
Please consult the FAQ for as to how to format your post.
This is the answer box; if you want to write a comment instead, please use the 'add comment' button.
Live preview (may slow down editor)   Preview
Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:
p$\hbar$y$\varnothing$icsOverflow
Then drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds).
To avoid this verification in future, please log in or register.




user contributions licensed under cc by-sa 3.0 with attribution required

Your rights
...