PTOLEMY project: Princeton Tritium Observatory for Light, Early-Universe, Massive-Neutrino Yield

  • Awardees
  • Christopher G. Tully, Ph.D. Princeton University
Year Awarded


The Princeton Tritium Observatory for Light, Early-universe, Massive-neutrino Yield, called PTOLEMY after the second-century astronomer and mathematician, will be the first instrument built with the goal of direct detection and measurement of the present-day relic neutrino density. Relic neutrinos are a fundamental element of Big Bang cosmology with their ubiquitous presence throughout all cosmological epochs leaving indirect signatures at every step in present-day observables. PTOLEMY leverages the unique tritium handling capabilities of the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the expertise at the Savannah River National Laboratory (SRNL) to construct the highest capacity, largest surface area, single atomic layer tritium cell ever made. PTOLEMY involves the parallel development of several key technologies, from large-scale nano-fabrication of a graphene tritium cell to massively multiplexed SQUID readout of ultrahigh precision micro-calorimetry developed by collaborators at NASA Goddard (GSFC) and Argonne National Laboratory (ANL). In combination with the cosmic microwave background radiation (CMB), large-scale structure correlations from the Sloan Digital Sky Survey (SDSS), and future data from the Large Synoptic Survey Telescope (LSST), the data from PTOLEMY will fundamentally deepen the precision and reach of cosmological investigation.

Christopher Tully earned his Ph.D. in physics (1998) from Princeton University, and his B.S. in physics from the California Institute of Technology. He has been a professor of physics at Princeton University for 14 years and served as associate chair of the physics department. He was a CERN Fellow (1998 – 2000) and a recipient of a Sloan Fellowship in 2003 and the IBM Einstein Fellowship at the Institute for Advanced Study in 2010. He is author of the textbook Elementary Particle Physics in a Nutshell (2010), published by Princeton University Press, and of a chapter on 4pi detectors in the text 100 Years of Subatomic Physics published in 2013 by World Scientific.

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