IceCube Bean-Bag Toss

Activity/Demo overview:

  • The demo represents neutrinos coming from sources to be detected by the IceCube Observatory. The thrower stands on a mat and represents the source, the bean bag is the particle, and the board with nets is IceCube. 
  • The activity involves a set of bean bags, a target with 3 different holes, and, if space/time allows, a scale model of the IceCube detector made of LED strips in a frame.
    • The bean bags correspond to the neutrinos going through the detectors
    • The 3 different holes correspond to the three different types of signals IceCube commonly sees: Astrophysical Muon Neutrino (track), Astrophysical Electron/Tau Neutrino (cascade), and Atmospheric Muon Neutrino (track)
    • When a participant throws a bean bag into one of the holes, that represents a neutrino being detected by IceCube
    • If the scale model setup is included, getting a bean bag into one of the holes will light up LEDs in the model corresponding to a real event of the type for that hole
    • The LED model is intended to link the neutrinos to the actual hardware. It lights up exactly how the optical modules in IceCube light up, giving a tangible recognition of the neutrino event to the people engaging with the activity.
  • There are two sets of this activity; one without the scale model which can be setup almost anywhere, at a fair or festival, and one with the scale model which requires more dedicated space (like the WID atrium)

Activity/Demo Instructor Notes:

  • How to set it up
    • If the scale model is not included, it is simply placing the board with the nets at one point, and then the “throwing circle carpet” with the box of bean bags about 8 feet away
    • If the scale model is included, there is a much more intricate setup, contact Jim Madsen ( or Ellen Bechtol (
  • What did you do + say that worked best?
    • To first engage a participant, I would say something along the lines of:
      • “This is a model of the IceCube experiment. You’re going to stand on the carpet and imagine you’re an exploding star far away from Earth. You’re gonna throw a bean bag at the target and try and get it inside. If you make it in the net, that’s like a particle from the star reaching IceCube.”
    • Then, if they are interested/older, I go into describing IceCube as a cubic kilometer of ice at the South Pole filled with little cameras, and that we see neutrinos coming from these high energy events in the universe, and neutrinos are hard to see so we need this huge amount of ice to detect it.
    • Other facts you can share with the public:
      • For younger people
        • Neutrinos are a particle and they are everywhere — you have 100 trillion neutrinos passing through your body every second — but they almost never interact with anything.
        • Our experiment is at the South Pole. Right now it’s [winter/summer] and about [insert temp]. That’s really cold!
      • For older audiences
        • IceCube is a detector buried in the ice at the South Pole that detects neutrinos. This LED model shows how we study a neutrino detection. The color of the lights corresponds to which part of the detector first sensed light from a neutrino interaction. Our sensors also tell us how much energy they detected and this helps us understand more about the interaction. [you can then point them to a DOM on display or to the poster showing the size of the detector]
    • Many of the younger participants (3-6) who used the activity just wanted to throw bean-bags in the holes
      • For them, just encouraging them when they throw it close to a hole or get it in is exciting
      • If they do get it in a hole, try to draw their attention to the LEDs that will light-up, sometimes that would really excite them
    • For older participants, when they get a bean bag into a hole, draw their attention to the model, and engage them in the shape that the lights create
      • If it is a cascade, ask them what kind of shape they see (ball-ish), and explain that all the energy is being deposited right there
      • If it is a track, ask them what direction they think it went in, and where on the Earth that it came from based off the direction
        • Upgoing: astrophysical, the Earth filters
        • Downgoing: atmospheric, large background
  • What would you not do or say?
    • I would not try to get technical about the how of the experiment, unless the participant is eager for that. Instead the take-away should be that we are seeing these particles from far away, and the throwing is mimicking that mechanism.
      • If it is a younger person accompanied by someone older, talk to the older person about IceCube as a telescope, usually this can happen while the younger person is throwing the bean bags

Zachary Curtis-Ginsberg, 2022-23 Wonders of Physics Outreach Fellow