Colloquium

Going Underground to Look at the Sun

Or studying the most elusive particles using big science and other (seemingly) oxymoronic tales.

Paul LaMarche ’75
Physics Department
Princeton University
Wednesday, April 19, 2006
Higgins 310, 4 pm

The study of solar neutrinos and the effort to determine the mass difference between types is being undertaken by several very large experiments around the world. The scale of these experiments is at least several orders of magnitude larger than tabletop laboratory experiments and they involve the participation of hundreds of people. The elusive neutrino is fantastically difficult to detect, driving these detectors to immense mass and deep underground to avoid a large part of the constant battering of cosmic ray induced backgrounds. The first solar neutrino detector, built by Ray Davis and colleagues in the Homestake mine in 1967, measured the now famous solar neutrino defect. This defect is attributed to the oscillation of neutrinos from one type to another. I shall discuss a modern day version of this experiment about to be launched in the Gran Sasso Mountains, east of Rome, the Borexino Experiment. I shall discuss the storied history of the neutrino, the difficulty of measuring this particle, significant results from the Kamiokande Experiment, and the ramifications of neutrino mass, yet one more oxymoron with its postulated effect on universe as a whole. This will lead to discussion of the recent WMAP satellite results on the bounds of neutrino mass. Finally, I shall discuss the implications of managing large experimental projects, trying to chart an organized path though such projects without stifling the creative talents of its participants, yet another (seeming) oxymoron.