JANET CONRAD, Professor of Physics
Research Interests
The lightest and most elusive of the known matter particles are neutrinos. Their
number far exceeds the atoms in the universe. Yet we know surprisingly little
about these articles. It is only within the last decade, for example, that we came
to realize these particles have mass, albeit very tiny. This became clear when
neutrinos were shown to live a double life, transforming from one type into
another through the quantum mechanical effect of neutrino oscillations,
an effect that requires neutrino mass.
While their masses may be small, the impact of neutrinos
on particle physics is enormous. In the Standard Model, which
describes particle interactions, neutrinos are massless. So the
discovery of mass challenges us to rethink our theory. It also
provokes us to ask: “What other properties of neutrinos might be
outside of the Standard Model?”
Janet Conrad’s research uses neutrinos as tools to probe for new
physics. Until 2007, she was co-spokesperson of the MiniBooNE
experiment, which searched for a new neutrino beyond the three
types known in the Standard Model. This was motivated by an oscillation
result from the Liquid Scintillator Neutrino Detector (LSND) experiment at
Los Alamos, which indicated an oscillation wavelength inconsistent with other
experiments, perhaps pointing to the existence of a fourth neutrino species. Mini-BooNE provided a strict test of this hypothesis, and ruled out the explanation of
a fourth type of neutrino.
However, while one neutrino anomaly has been resolved, another has sprung
up. At low neutrino energy, MiniBooNE saw an excess of events above the Standard
Model expectation and inconsistent with neutrino oscillations. Its source
remains a mystery, which is best explored through a more sensitive detector. To
this end, Conrad is involved in the MicroBooNE experiment, which is developing
a state-of-the-art detector that makes use of liquid Argon.
At the same time, Conrad has shifted her focus to exploring the properties
of the three Standard Model species. While many combinations of oscillations
between neutrinos have been observed, there is one which is yet to be seen. The
purpose of the Double Chooz experiment, on which Conrad collaborates, is to
observe, for the first time, this rare transmutation.
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Biographical Sketch
Janet Conrad received her B.A. from Swarthmore College in 1985, M.Sc. from
Oxford University in 1987, and Ph.D. from Harvard in 1993. She began as a
postdoctoral associate at Columbia University and was promoted to Assistant
Professor in 1996. Most recently, she was the Walter O. Lecroy Professor of
Physics at Columbia University.
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Selected Publications
Forthcoming.
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