In particle physics, a massless particle is an elementary particle whose invariant mass is zero, the discovery of this phenomenon, known as neutrino oscillation, led to which Japanese physicist, known for neutrino experiments at the Kamiokande and its successor, Super-Kamiokande, shared the 2015 Nobel prize in physics?
Massless particle In particle physics, a massless particle is an elementary particle whose invariant mass is zero. The two known massless particles are both gauge bosons: the photon (carrier of electromagnetism) and the gluon (carrier of the strong force). However, gluons are never observed as free particles, since they are confined within hadrons. Neutrinos were originally thought to be massless. However, because neutrinos change flavor as they travel, at least two of the types of neutrinos must have mass. The discovery of this phenomenon, known as neutrino oscillation, led to Canadian scientist Arthur B. McDonald and Japanese scientist Takaaki Kajita sharing the 2015 Nobel prize in physics.
Kamioka Liquid Scintillator Antineutrino Detector The Kamioka Liquid Scintillator Antineutrino Detector (KamLAND) is an electron antineutrino detector at the Kamioka Observatory, an underground neutrino detection facility near Toyama, Japan. The device is situated in a drift mine shaft in the old KamiokaNDE cavity in the Japanese Alps. The site is surrounded by 53 Japanese commercial nuclear reactors. Nuclear reactors produce electron antineutrinos (formula_1) during the decay of radioactive fission products in the nuclear fuel. Like the intensity of light from a light bulb or a distant star, the isotropically-emitted formula_1 flux decreases at 1/R per increasing distance R from the reactor. The device is sensitive up to an estimated 25% of antineutrinos from nuclear reactors that exceed the threshold energy of 1.8 megaelectronvolts (MeV) and thus produces a signal in the detector.