Using the CMS e-Lab



CMS Online Data Analysis

The QuarkNet CMS Ray e-Lab ( contains a large data set of events in the Compact Muon Solenoid detector in the Large Hadron Collider at CERN and analysis tools for students and teachers to draw physical meaning from that data.

This note introduces the resources to help students and teachers use the CMS e-Lab and to find investigations they can do.


How to use the CMS e-Lab

We have a series of three screencasts that can get the user started:

  • Introduction and Overview. This shows the main features of the e-Lab and how to access them.
  • Data Analysis I. The user is shown analysis of a large set of dimuon events and how to pick out and work with different features of the mass plot.
  • Data Analysis II. Here the user sees a smaller set of dimuon events limited to the 2-5 GeV invariant mass range and learns about different ways to analyze that data through multiple plots.


Suggested investigations


  • J/Psi mass (must bin appropriately) 
  • compare Z→mumu and Z→ee
  • Find how many peaks correseponding to real particles are in the 100k dimuon spectrum
  • Show advantages and disadvantges of log x and log y plots
  • Investigate use of bin widths to understand data
  • global muon study (compare plots with global muons only to those with lower quality tracks allowed)
  • charge study (compare plots of the same data with different final state electric charge configurations)



  • estimate upper limit of lifetime of particle from width of peak
  • find cosmic rays in data
  • use Correlated Charts to learn how variables affect each other
  • investigate parameters of detector using theta and eta plots
  • study and characterize background(s) in plot(s).


Further resources

Learn more about CMS and the LHC: