Senior Member, KICP
Ph.D., Princeton University, 2006
Jeff McMahon is an experimentalist who studies cosmology and fundamental physics through measurements of the cosmic microwave background (CMB). Measurements of the temperature fluctuations of the CMB have yielded a rich set of cosmological results including evidence that the universe is spatially flat; measurement of the contents of the universe including dark matter and dark energy; and constraints on inflation: the theory of our universe's first moments. While measurements of the CMB temperature are reaching maturity, CMB signals including its polarization, gravitational lensing, and small scale secondary anisotropies have yet to be fully exploited. Measurement of the spatial pattern of CMB polarization will constrain the energy scale of inflation which could provide a unique window into physics at the grand unification (GUT) energy scale. Measurement of CMB lensing will provide a tight constraint on the sum of the neutrino masses and through cross-correlations with external data sets will provide a measurement of astrophysical bias which will multiply the cosmological impact. Measurements of the CMB temperature at very small angular scales have potential to improve our understanding of galaxy clusters and dark energy.