Jeffrey P Filippini

Assistant Professor


Jeffrey P Filippini

Primary Research Area

  • Astrophysics / Gravitation / Cosmology
405 Loomis Laboratory

For more information


Professor Filippini earned his bachelor's degree in Chemistry and Physics from Harvard in 2002 and his Ph.D. in Physics from Berkeley in 2008. His doctoral work focused on the search for dark matter interactions in subterranean detectors. As a postdoctoral researcher at Caltech he developed balloon-borne and terrestrial instruments to measure the polarization of the cosmic microwave background radiation. He joined the faculty of the University of Illinois in 2014.

Research Statement

My research interests lie at the intersection between the universe's workings on its largest and smallest scales. We can now recount the life story of our cosmos in remarkable detail, yet our data reveal a humbling degree of ignorance about its workings. Our universe appears to be filled with forms of matter and energy unlike anything on Earth, and many key aspects of cosmic evolution remain to be understood. Solving these mysteries will demand new fundamental physics, and measurements at the "cosmic frontier" are poised to play a central role.

My work to date has employed novel sub-Kelvin detectors to address two mysteries of our cosmos: What is the nature of the dark matter that governs the dynamics of large-scale structure? What spurred the inflationary epoch that begins our narrative of cosmological history? This work bridges several sub-disciplines of physics and astrophysics, linking the grand questions of fundamental physics with the quantum phenomena that enable the most sensitive measurements. I am also broadly interested in new technologies and analysis techniques to address fundamental physics.

Observational Cosmology: Observations of the cosmic microwave background (CMB) have transformed our understanding of the universe. The next frontier of this endeavor is the measurement of the faint polarization of this primordial radiation field. A "B-mode" (curl) pattern in the CMB's polarization at degree angular scales is a unique prediction of inflationary models of the universe's early moments, and a possible a window onto energies far beyond those accessible at accelerators. I collaborate on several millimeter-wave polarimeters that employ large-scale bolometer arrays to search for this signature in the millimeter-wave sky. BICEP2 observed for three years from the South Pole with unprecedented sensitivity, and in 2014 reported a detection of B-modes at degree angular scales. The Keck Array and BICEP3 continue this program with ever-more-sensitive instruments observing at multiple frequencies. I lead the receiver team for SPIDER, the most instantaneously-sensitive CMB polarimeter yet deployed, which carried this technology on a long-duration balloon flight 36 km above the Antarctic ice in January 2015. There are opportunities for instrument development and data analysis for these and future instruments.

The Search for Dark Matter: The discovery that the universe is not made of the same stuff that we are must rank as one of the most profound of the 20th century; understanding the nature and phenomenology of this dark universe remains a compelling challenge for the 21st. There is now a wealth of evidence that the bulk of the mass that drives cosmic structure formation is in some exotic form, not to be found in the highly successful Standard Model of particle physics. If this "dark matter" possesses some non-gravitational interaction, a particle from the Milky Way's halo may occasionally scatter from an atomic nucleus in an experimental apparatus. Such scattering events may be detectable in the laboratory with a sufficiently massive and sensitive particle detector, if the rates of cosmogenic and radiogenic background events can be kept low enough. The Cryogenic Dark Matter Search (CDMS) collaboration searches for such interactions in arrays of low-temperature Ge and Si detectors. These detectors are particularly powerful in searches for low-mass (below 10 GeV/c2) dark matter candidates. A 100+ kg array of improved detectors is under development for SuperCDMS SNOLAB, recently approved as part of the second generation (G2) suite of dark matter experiments.

Semesters Ranked Excellent Teacher by Students

Spring 2016PHYS 213
Spring 2015PHYS 211