 For cross-checking purposes, CERN uses two main detectors. One of them is the compact muon solenoid, or CMS for short. It was designed to search for the Higgs boson and dark matter. The second detector is called ATLAS. It uses different technical solutions and a different magnet system. It is seven stories high. We'll take a closer look at this one. The detecting components in ATLAS are each designed to detect different kinds of particles. The pixel detector and semiconductor tracker contain layers of silicon, charged particles passing through the silicon, release electrons that float a millions of microscopic metallic spheres under the silicon layer. These are all electronically connected to the computer. It keeps track of their path. The transition radiation tracker can distinguish between different types of charged particles. It contains a large number of tubes filled with gas. Passing charged particles produce electrons that flow down a wire in each tube. Different particles produce different currents. A strong magnetic field is created around these inner trackers. Degenerated curves in particle paths enable us to calculate the particle's momentum, like we did at Slack. ATLAS has two calorimeters. Like the calorimeter we used in the Beta-DK experiment, they are used to measure the energy of the transiting particles. But these two don't use heating water. That would take forever. The electromagnetic calorimeter measures the energy of photons and leptons, like electrons and positrons. It contains many layers of lead and stainless steel that absorb the particles. Between the layers is liquid argon at minus 180 degrees centigrade. Immersed in the liquid argon is a copper grid. Passing particles drive electrons to the copper, and measuring the number gives us the energy of the particle. The hadronic calorimeter measures the same for hadrons, like protons, neutrons, and mesons. It is a large array of steel and scintillator sheets that create photons when struck by charged particles. Light fibers carry the light to intensity measuring devices. The light intensity gives us a measure of the energy of the hadrons entering the calorimeter. At the outer layer is a muon spectrometer, with a surface area the size of several football fields. In the attached chambers there are tubes, also filled with gas. The electrons that are generated by the passing muon drift to the center. This enables the system to determine its track. Here are a few examples. Electrons plow through the inner detector, leaving a trail before stopping in the electromagnetic calorimeter. Photons will act the same way in the calorimeter, but they do not leave any track through the inner detector since they have no charge. Protons leave a track, but will most likely pass through the electromagnetic calorimeter into the hadronic calorimeter. Neutrons behave in a similar way, but leave no track through the inner detector. Muons pass all the way through atlas, leaving tracks behind in every layer. And as was the case with beta radiation, neutrinos pass all the way through atlas without being detected at all.