Ghostbusting
E=hf. It therefore allowed the neutrino to be represented mathematically as the constructive and destructive interference of the wave functions of the two or three combinations of the different flavours (see figs.3 and fig.4).
Method 2: the Super-KamiokaNDE (Super Kamioka Nucleon Decay Experiment)
In order to test the theory of neutrino oscillation, one of the largest detectors in the world was built under Mount Ikeno in Japan. Called the Super-Kamiokande, it is a 50,000-ton cylindrical tank of water located 1km below the surface in the Mozumi Mine, and it aims to detect neutrinos from every corner of the universe, not just those created from our sun as in the Davis experiment. The inside of the tank is covered in 11,146 ‘ photo-multiplier tubes ’ (PMTs) – which essentially are photon detectors, able to convert the detection of a single photon to an electronic signal. The photons they detect are from the faint light emitted from Cherenkov radiation.
Cherenkov radiation
When a charged particle such as an electron or muon moves through a medium faster than the speed of light in that medium (phase velocity of the photon), a cone of light is emitted around the path of the particle, with the charged particle located at the apex of the cone. This cone of light is known a Cherenkov radiation and is analogous to a sonic boomwhen a jet surpasses the speed of sound in air. The velocity required for Cherenkov radiation inwater is just over 75% of the speed of light in a vacuum.
u
Fig.5 - Cherenkov Radiation Cone of light emitted radially from centre of cone along path u
In the Super-K detector, physicists primarily look at two charged particles when investigating neutrinos: electrons and
muons, both have a -1 charge. They traverse the water at high velocities after interactions with neutrinos and consequently emit Cherenkov radiation. The cone of light would then be detected and mapped out by the 11,000 PMTs. From this data the analysts are able to tell which particles are involved in the reaction – fuzzy edges of the perimeter of the cone, or sharper edges for muons – , the velocity of the particles calculated from the angle θ [illustrated in fig.5 ], and also the energy of the particle shown by the intensity of the light emitted. Because neutrinos cannot be directly observed, the Super-K detects the by-products of neutrinos interactions with protons and neutrons in highly purified water. These interactions are called Wboson interactions as they involve the weak force, equating to the exchange of virtual particles W- and W+ bosons. During these reactions the neutrino changes to its corresponding lepton:
Fig.6.2 Electron neutrino to electron
Fig.6.1 Muon neutrino to muon
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