Eric Dahl

Assistant Professor
Joint Appointee Associate Scientist at Fermi National Accelerator Laboratory
PhD, Princeton University, 2009

Eric Dahl's research addresses the problem of detecting and identifying the dark matter in our galaxy. A variety of astrophysical and cosmological observations agree that there is 5x more "dark matter" in the universe than "light matter" (electrons, protons, and neutrons). No known particle can make up this dark matter, making the dark matter problem our strongest piece of evidence for particle physics beyond the standard model.

Professor Dahl's group is part of the COUPP/PICASSO Collaboration, one of several collaborations racing to unambiguously detect dark matter particles as they pass through terrestrial detectors. COUPP uses bubble chambers deployed 6800 feet underground at SNOLAB to look for WIMPs (Weakly Interacting Massive Particles), one of the leading candidates for dark matter. The ~10-keV recoiling nucleus that is the signature of a WIMP interaction will nucleate a single bubble in the superheated fluid target of the bubble chamber. By tuning the degree of superheat, the chambers can be made completely insensitive to recoiling electrons from beta-decays and gamma-interactions -- backgrounds that plague other WIMP detection experiments. The COUPP bubble chambers also employ ultrasonic acoustic detectors to distinguish nuclear recoils from alpha-decays, and high-resolution, high-speed cameras that resolve multi-bubble events from neutrons, making this a background-free technology for WIMP detection.

The COUPP-4 experiment (4-kg CF3I target) has produced the world-leading limits from a direct detection experiment for the spin-dependent WIMP-proton cross-section. A larger detector, COUPP-60, will turn on at SNOLAB in March 2013, and the next-generation ton-scale bubble chamber is currently being designed. The group at Northwestern works with Fermilab and the University of Chicago on the design, operation, and analysis of these bubble-chamber dark-matter detectors, and is also launching several smaller devices, both on campus and at the Fermilab Test Beam Facility, to calibrate the bubble chamber response to various interactions.

Selected Publications

E. Behnke et al. “First dark matter search results from a 4-kg CF3I bubble chamber operated in a deep underground site.” Phys. Rev. D 86,

052001 (2012). DOI:10.1103/PhysRevD.86.052001

P. Sorensen and C.E. Dahl. “Nuclear recoil energy scale in liquid xenon with application to the direct detection of dark matter.” Phys. Rev. D 83, 063501 (2011). DOI:10.1103/PhysRevD.83.063501

E. Behnke et al. “Improved Limits on Spin-Dependent WIMP-Proton Interactions from a Two Liter CF3I Bubble Chamber.” Phys. Rev. Lett.

106, 021303 (2011).  DOI:10.1103/PhysRevLett.106.021303

P. Sorensen et al. “The scintillation and ionization yield of liquid xenon for nuclear recoils.” Nucl. Inst. Meth. A 601, 339–346 (2009). DOI:10.1016/j.nima.2008.12.197

J. Angle et al. “First Results from the XENON10 Dark Matter Experiment at the Gran Sasso National Laboratory.” Phys. Rev. Lett. 100, 021303 (2008). DOI:10.1103/PhysRevLett.100.021303

T. Shutt, C.E. Dahl, J. Kwong, A. Bolozdynya and P. Brusov.

“Performance and fundamental processes at low energy in a two-phase liquid xenon dark matter detector.” Nucl. Inst. Meth. A 579, 451–453 (2007). DOI:10.1016/j.nima.2007.04.104

E. Aprile, C.E. Dahl, L. deViveiros, R.J. Gaitskell, K.L. Giboni, J.

Kwong, P. Majewski, K. Ni, T. Shutt and M. Yamashita. “Simultaneous Measurement of Ionization and Scintillation from Nuclear Recoils in Liquid Xenon for a Dark Matter Experiment.” Phys. Rev. Lett. 97, 081302 (2006).  DOI:10.1103/PhysRevLett.97.081302

 

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August 26, 2013