International Particle Physics Outreach Group
Hands on Particle Physics Masterclasses

Various packages with data from experiments at the LHC, from MINERvA, Belle II, or Pierre Auger as well as a package on Particle Therapy are available from the web:


Two measurements with ALICE data are available.

Looking for strange particles in ALICE 2023 can be found here. In 2021 a web-based version of the measurement was developed (it needs no installation and can be done using a browser); the current version, developed in 2022, also includes saving the results of the measurement on a server; it can be found here.
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.

Supporting material:

Measurement of the nuclear suppression factor RAA with ALICE 2023 can be found here. For online Masterclasses a Python-based version of this measurement is available here (German only)."
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 2023 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 2023 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:

Supporting installation videos/screencasts for the Z-path:


The 2023 measurement with CMS data is available here. Please choose WZH 2,4-lepton PATH. A recent version of Firefox, Chrome, Edge, or Safari is required for iSpy-webgl. If using offline (e.g. from DVD), open iSpy with Firefox ver 7 or greater. The CMS measurement includes:

  • Discrimination of particles based on decays into single lepton plus missing ET, dilepton, four-lepton, or "zoo" decays.
  • Calculation of particle ratios
  • Creation of 2-lepton and 4-lepton mass plots of particles
  • Online 3-dimensional event display with explanatory screencast
  • Available in Chinese, Dutch, English, French, Italian, German, Hebrew, Hungarian, Italian, Japanese, Lithuanian, Polish, Portuguese, Russian, Spanish, Turkish.

Supporting material:

  • Documentation for Tutors: webpage, pdf
  • Screencasts (show students how to install the software and perform the analysis)
  • 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 LHC Masterclass Library

The 2023 measurement with LHCb data is available here. 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:


The 2023 measurement with MINERvA data is available here. The MINERvA measurement includes:

  • Signal vs. noise – students select only events which consist of a clean muon track and a clean proton track from the same vertex.
  • Conservation of momentum – students calculate beam energy and distribution of momenta of neutrons in the carbon nucleus from momenta of muons and protons ejected by weak interaction with beam muon neutrinos.
  • Discovery of Fermi motion – students see that there is a distribution of momenta transverse to the beam best explained by motion of neutrons in the nucleus.
  • Testing of models – students use combined data to calculate the size of the carbon nucleus using the uncertainty principle, first treating the neutrons in the nucleus as free and then as a Fermi gas.

    Supporting material:

  • Documentation for Tutors: webpage
  • Physics discussion: webpage
  • Screencasts (show students how to install the software and perform the analysis)
  • Embedded videos in website
  • Resources for physicists, teachers, and students in Neutrino Masterclass Library
Belle II

The 2023 measurement with Belle II data is available here. The Belle II measurement includes:

  • Visualization of Events - Display of the collision events in the Belle II spectrometer.
  • Introduction to the invariant mass - combining the masses and momenta of two selected particles.
  • Discovery of new particles - students describe a two body decay and search for new particles on the sample of about 5 mio. of events from Belle and Belle II experiments.
  • Fitting and determining the mass and yields of the discovered particle.
Pierre Auger

The 2023 measurement with the Pierre Auger Observatory public data is available here. The measurement includes:

  • Visualization of events using an interactive display of the observatory.
  • Separation of surface-detector stations with signal from those with background.
  • Visual reconstruction of the arrival direction of the primary cosmic ray.
  • Fitting the data to determine the energy of the primary cosmic ray.
  • Application of criteria to select events which point to the source.
  • Interpretation of sky maps in different coordinate systems.
Particle Therapy

The 2023 Particle Therapy Masterclass is available here.

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