The 2015 Nobel Prize in Physics was given on October 6 to Takaaki Kajita of the Superkamiokande experiment and to Arthur McDonald of the Sudbury Neutrino Observatory. The work at both those sites is thoroughly discussed in The Cosmos (see Section 12.7, p. 322-325) about the solar-neutrino experiment.
By showing definitively that a mix of the three types of neutrinos reaches the Earth, combining the knowledge that only electron-neutrinos leave the Sun shows that neutrinos change in type en route. Only if neutrinos have mass can such changes take place, so the discovery is a major challenge to the Standard Model of particle physics.
This is the third Nobel Prize for neutrino research. Half the 1995 Nobel Prize went Fred Reines for the discovery of neutrinos in an atomic-reactor beam (his co-discoverer, Clyde Cowan, having died before the prize was given, making him ineligible). Half the 2002 Nobel Prize went to Ray Davis, who ran the chlorine version of the neutrino experiment at the Homestake Mine, and Masatoshi Koshiba, who was in charge of Kamiokande (the Neutrino Detection Experiment [NDE] in the Kamioka mine in Japan). John Bahcall from the Institute for Advanced Study, who had done the bulk of the theoretical work involved, was omitted from the prize, unfortunately (again, as the prize is not awarded posthumously).
Links: 2015 Nobel Prize in Physics at the Royal Swedish Academy of Sciences; Dennis Overbye’s analysis for the NY Times (including a discussion of the next investigations via The Deep Underground Neutrino Experiment, DUNE).