International Particle Physics Outreach Group
Hands on Particle Physics Masterclasses

Six different packages with data from one of four experiments at the LHC are available from the web:


Two measurements with ALICE data are available.

Looking for strange particles in ALICE 2019 can be found here. Under „Installation“ you can download the current version of the measurement.
The measurement includes:

  • Visual identification of strange particles (V0s : Ks, Λ, anti-Λ) from their decay pattern, combined with calculation of their invariant mass.
  • Analysis of large samples of lead-lead data in order to find the number of Ks, Λ, anti-Λs in different centrality regions
  • Calculation of yields for Ks, Λ, anti-Λ and strangeness enhancement factors by comparing to proton-proton data
  • Available in Czech, English, French, German, Greek, Italian, and Portuguese.

Supporting material:

More information:

In addition, another version can be downloaded (and unzipped) here (Created to solve problems when running with ROOT6).

Virtual box/Virtual machine:

If you need to run the program using virtual box, here is the procedure to follow:
  • Go to github.
  • Click on „Installation“ and follow the instructions to create the virtual machine, according to the operating system (Linux/MacOsX/Windows)
  • If the installation is successful, to run the programs you need to open a terminal and give the command
    • ./ -e Strangeness -p 1 -l en (for the first part of the measurement, the visual analysis)
    • ./ -e Strangeness -p 2 -l en (for the second part of the measurement, the large scale analysis)
  • A previous version of the virtual machine can be downloaded from here (go to "Installation").

Measurement of the nuclear suppression factor RAA with ALICE 2019 can be found here. The measurement includes:

  • Measurements of charged particle momentum distributions in pp and Pb-Pb collisions
  • Event display based analysis of pp and Pb-Pb collisions
  • Large scale numerical analysis of Pb-Pb collisions
  • Available in English

Supporting material:


Two measurements with ATLAS data are available, the W path and the Z path.

The W path 2019 is available here. It includes:

  • Working with event displays from data taken at ATLAS
  • Determine the ratio W+/W- to reveal the inner structure of the proton
  • Find Higgs events, measure opening angle between 2 leptons and plot angular distribution
  • Supported languages: Czech, Danish, English, French, German, Greek, Italian, Polish, Portuguese, Slovak, Spanish.

Supporting material for the W-path:

The Z path 2019 is available here. It includes:

  • Working with event displays from data taken at ATLAS
  • Master the invariant mass technique to study and measure the Z boson and other resonances decaying into 2 leptons, and look for new physics
  • Search for the Higgs boson decay to 2 photons and 4 leptons from ZZ
  • Supported languages: Czech, Danish, English, French, German, Greek, Italian, Norwegian, Polish, Portuguese, Slovak, Spanish, Turkish.

Supporting material for the Z-path:


The 2019 measurement with CMS data is available here. Please choose WZH PATH. A recent version of Firefox, Chrome, or Safari is required for iSpy-webgl. Open iSpy from DVD with Firefox ver 7 or greater. The CMS measurement includes:

  • Discrimination of particles based on decays into muons and other possible products
  • Calculation of particle ratios
  • Creation of mass plots of particles
  • Online 3-dimensional event display with explanatory screencast
  • Available in Chinese, Dutch, English, French, Italian, German, Hebrew, Hungarian, Italian, Japanese, Polish, Portuguese, Russian, Spanish, Turkish.

Supporting material:

  • Documentation for Tutors: website, pdf.
  • An introductory talk is available here.
  • Embedded videos in website
  • CMS videos
  • Animation of the CMS experiment and detector elements
  • Resources for physicists, teachers, and students in Masterclass Library

The 2019 measurement with LHCb data is available here. Please choose the measurement of the lifetime of the charm particle called D0. The LHCb measurement includes:

  • Use an event display of the proton-proton collisions inside the LHCb detector to search for charmed particles and separate this signal from backgrounds.
  • Fit functional forms for the signal and background to the data in order to measure the number of signal events in the data sample and their purity (defined as the fraction of signal events in the total sample).
  • Obtain the distribution of signal events in a given variable by taking the combined distribution of events in the data sample (which contains both signal and background events) and subtracting the background distribution. The result of the fit in the previous step is used to find a sample of pure background events for subtraction, and to compute from the signal yield and purity the appropriate amount of background which should be subtracted.
  • The signal you will be looking at decays exponentially with time, analogously to a radioactive isotope. You can now use the sample of events passing the previous step to measure the "lifetime" of the signal particle.

Supporting material:

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