International Physics Masterclasses
W stien
Welcome to the W path. If you follow this path you will work with real data recorded by ATLAS, a particle detector at the Large Hadron Collider (LHC). In the course of your scientific journey, you will learn how to identify elementary particles, spot event topologies, and deduce information from large bodies of data.
To do this, you will have to do a bit of detective work. Lots of particles are created in a proton-proton collision (a so-called "event"). The key task is to search for specific elementary particles in these events and link them to the physical processes that might have spawned them. In doing so you get to know the challenges physicists have to face.

The animation below will draw your attention to the main actor – the W particle. It plays an important role in radioactive decay, e.g. that of Potassium-40. Potassium-40 is an unstable isotope with 40 nucleons (19 protons and 21 neutrons) in the nucleus and decays by emission of a negative or positive beta particle. We have chosen potassium as an illustration because it is essential for the human body and is responsible for the water content in our cells. It is also an important electrolyte in body fluids. About every 9000th potassium atom of the approximately 100 grams of potassium in your body is potassium-40. Our animation shows how particle physicists see the beta decay which occurs in your body:


Tim Herrmann, Konrad Jende, CERN, July 2010

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