The nuclear fusion processes that power the Sun take place at such high temperatures that the nuclei of atoms are able to fuse together, a process that results in the creation of very large numbers of fundamental particles called neutrinos. Neutrinos only interact through the weak interaction and gravity and therefore can penetrate out from the core of the Sun and through the Earth with little or no interaction. It is these neutrinos from the Sun that are the subject of our measurements with the Sudbury Neutrino Observatory (SNO), 2 km underground in a mine near Sudbury, Canada. With the use of heavy water as a central element in the design of SNO it was possible to determine clearly that electron neutrinos change to one of the other active flavors before reaching our detector, a property that requires that they have a mass greater than zero. Both of these fundamental neutrino properties are beyond the predictions of the Standard Model for elementary particles. Extensions of the Standard Model to include these neutrino properties can give us a more complete understanding of our Universe at a very basic level., Arthur B. McDonald ; přeložil Ivan Gregora., and Obsahuje bibliografii
V roce 1918 zaznamenal detektor Kamiokande v toku atmosférických neutrin neočekávaný deficit mionových neutrin. V té době se za možné vysvětlení považovaly neutrinové oscilace. Posléze, v roce 1998, při studiu atmosférických neutrin detektorem Super-Kamiokande byly neutrinové oscilace objeveny, což vedlo k závěru, že neutrina mají hmotnost. Cítím, že jsem měl mimořádné štěstí, protože jsem se tohoto vzrušujícího objevu od samého počátku účastnil. Objev nenulových hmotností neutrin otevřel okno ke studiu fyziky nad rámec standardního modelu fyziky elementárních částic, zejména fyziky na škále velmi vysokých energií, jakou je velké sjednocení interakcí elementárních částic. Současně však zbývá mnoho věcí, které je třeba pozorovat na samotných neutrinech. Další studium neutrin by nám mohlo poskytnout informace, které mají fundamentální význam pro naše porozumění přírodě, jako např. původ hmoty ve vesmíru., An unexpected muon neutrino deficit was observed in the atmospheric neutrino flux by Kamiokande in 1988. At that time neutrino oscillation was considered as a possible explanation for the data. Subsequently, in 1998, through the studies of atmospheric neutrinos, Super-Kamiokande discovered neutrino oscillations, establishing that neutrinos have mass. I feel that I have been extremely lucky, because I have been involved in the excitement of this discovery from its very beginning. The discovery of nonzero neutrino masses has opened a window to study physics beyond the Standard Model of elementary particle physics, notably physics at a very high energy scale such as the grand unification of elementary particle interactions. At the same time, there are still many things to be observed in neutrinos themselves. Further studies of neutrinos might give us information of fundamental importance for our understanding of nature, such as the origin of the matter in the Universe., Takaaki Kajita ; přeložil Ivan Gregora., and Obsahuje bibliografii