josephf@mit.edu Phone: 617.253.3817 Fax: Address: 26-568 Related Links: Sudbury Neutrino Observatory (SNO) KATRIN Experiment Braidwood Experiment

Research Interests

An astonishing culmination of discoveries taking place over the last decade has led to a revolution in our understanding of neutrinos–one of nature’s most elusive particles. Whereas just ten years ago it was commonly accepted that neutrinos were massless particles, a number of key experiments have shown that concept was incorrect. Experiments studying neutrinos from atmospheric, solar, and reactor sources have shown conclusively that neutrinos change flavor and, as a consequence, have a very small but finite mass. This serves to remind us that the standard model of nuclear and particle physics is incomplete. Knowledge of the neutrino mass can provide direction as how to extend that model.

Formaggio’s research is focused in exploring the properties of neutrinos through three areas of experimental research:

• SNO: Located in a nickel mine deep underneath the Northern Ontario soil, the Sudbury Neutrino Observatory (SNO) has been studying neutrinos produced in the solar core. In 2001, SNO helped solve the so-called “solar neutrino problem,” by proving that neutrinos produced in the solar core undergo flavor transformation, a unique signature of neutrinos possessing a finite mass. The SNO continues to accumulate data to this day and to make important contributions to our understanding of neutrinos and solar physics.

• KATRIN: The scale of neutrino masses still remains an open question that is of great importance for many areas of physics, including particle physics and cosmology. A direct measurement of the neutrino mass would therefore provide independent and valuable input to our understanding of the universe and how it evolves over time. Formaggio is currently involved in the construction of KATRIN, a next-generation tritium beta decay experiment geared at directly measuring the neutrino mass down to fractions of an electron volts.

• Braidwood: By studying how neutrinos of a certain species can transform into other types of neutrinos (a phenomenon also known as neutrino oscillations) can provide a unique window into understanding why the universe we live in today is dominated by matter. Formaggio is also involved in the design of the Braidwood experiment, which uses neutrinos created in reactor cores to make high-precision measurements of neutrino oscillations.

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Biographical Sketch

Joseph Formaggio received his B. S. degree at Yale University in physics in 1996. Thereafter, he received his Ph.D. in physics from Columbia University, where he did his dissertation on neutrino physics by analyzing data taken at the NuTeV experiment located at the Fermi National Laboratory. His research focused on searches for exotic particles predicted by certain theoretical extensions of the standard model of particle physics. In 2001, he joined the Sudbury Neutrino Observatory as a postdoctoral fellow at the University of Washington, where he was later appointed as a research assistant professor. Professor Formaggio lives with his wife, Jaymi, and his two children, Joshua and Coby.

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Selected Publications

“Backgrounds to Sensitive Underground Experiments,” J. A. Formaggio and C. J. Martoff, Ann. Rev. of Nucl. and Part. Sci. 54, 361 (2004).

“Measurement of the Total Active 8B Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity,” Q. R. Ahmad et al., Phys. Rev. Lett. 92, 181301 (2004).

“Direct Evidence for Neutrino Flavor Transformation from Neutral-Current Interactions in the Sudbury Neutrino Observatory,” Q. R. Ahmad et al., Phys. Rev. Lett. 89, 011301 (2002).

“Measurement of the Day and Night Neutrino Energy Spectra at SNO and Constraints on Neutrino Mixing Parameters, ” Q. R. Ahmad et al., Phys. Rev. Lett. 89, 011302 (2002).

“A Precise Determination of Electroweak Parameters in Neutrino Nucleon Scattering,” G. P. Zeller et al., Phys. Rev. Lett. 88, 091802 (2002).

“The Potential for Neutrino Physics at Muon Colliders and Dedicated High Current Muon Storage Rings,” I. Bigi et al., Phys. Rep. 371, 151 (2001).

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