I will describe the history of the discovery/invention of Neutrinos, starting with the discovery of radioactivity by Henri Becquerel almost 115 years ago. It took the next 35 years before the neutrino was invented and another 25 years before it could be "discovered" experimentally. From 1956 to 2000 the remaining two kinds of neutrinos were found, and the story of neutrinos is intimately tied to the history of particle physics itself over this period. Along the way, we will cover the subject of neutrino oscillations or neutrino metamorphosis, which is related to the neutrino masses and mixing. We discuss the wide variety of sources of neutrinos ranging from the earth and the sun to nuclear reactors and accelerators, as well as supernova (and other astrophysical objects) and the early universe. Finally some applications of neutrinos which are very speculative and futuristic will be briefly described.
Sandip Pakvasa(B. Sc. Baroda 1954, M. Sc. Baroda 1957, Ph. D. Purdue 1965), Professor of Physics at University of Hawaii since 1973. Professor Pakvasa was elected to the Fellowship of American Physical Society in 1976. He was awarded the University of Hawaii Regent's Medal in 2009. Among many interesting and important research contributions, two areas where professor Pakvasa have made important contributions are mostly related to today’s colloquium. In 1975, he wrote a paper with Hirotaka Sugawara in 1976 in which they brought the ground-breaking paper by Kobayashi and Maskawa to the attention of the community and showed that their proposal was able to account for the observed CP violation in the K system. Eventually, the Kobayashi- Maskawa proposal proved to be the correct idea with final confirmation in 2001 leading to the Physics Nobel Prize for Kobayashi and Maskawa in 2008. As an appreciation of the role played by the paper of Pakvasa and Sugawara, they were invited to attend the Nobel ceremony by Kobayashi in in Stockholm December 2008. In 1977, Pakvasa with Sugawara, and Lee and Shrock wrote a paper on the mass-mixing and oscillations of three neutrinos, in which a 3x3 complex mixing was considered for the first time and several phenomenological issues about neutrino mixing and oscillations were also raised, this was a pioneering paper. In 1980, Pakvasa wrote two very important papers: one on the matter effects in oscillations of three neutrinos and one on the neutrino oscillations in presence of both Dirac and Majorana mass terms. The first one predicted what is now known as the MSW effect, although they did not apply it to the solar neutrinos! The second one is essentially the first example of oscillations into sterile neutrinos.