UHM Physics Department Colloquia

The Saga of Atmospheric Neutrinos

by John Learned (University of Hawaii)



2505 Correa Road

Neutrinos, those mysterious ghostly elementary particles, are generated copiously by cosmic rays impinging on the atmosphere, whereupon they penetrate the earth, mostly unimpeded. With huge detectors for observing some rare neutrino collisions, we can detect a few of these elusive particles, and indeed measure their properties. This began in the 1960's in deep mines in South Africa and India, and came into serious observations in the 1980's when experiments (particularly one called IMB, in which UH was engaged) first detected something awry in the observed ratios of two of the (three) neutrino types.  This initiated a worldwide controversy known as the muon neutrino anomaly, which was only (mostly) resolved in 1998 with the discovery of muon neutrino oscillations by the SuperKamiokande (SK) experiment.  SK received the Nobel Prize for this work in 2015.

The talk will review the basic story, but aims to explain how real science on the leading edge almost always confuses the participants with false leads, errors and distracting hypotheses. In our teaching of science we generally present a nice logical sequence, without dead ends, wrong trails and such. Real science does not proceed in this way but presents a struggle, often in the dark, a wandering until the scientific truth becomes consensus clear. This was the case with the discovery of neutrino mass and mixing, uncovered without guidance from fundamental theory (and still a mystery).

As a participant in this nice drama over the last 50 years, I will recount the tale, hoping to being some idea of the intellectual chaos and excitement of the great game of untangling Nature's mysteries.

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