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Center for Nonlinear Studies |
We've known for some time, from several kinds of astronomical observations, that 85% of the matter in galaxies is "Dark"; interacting only gravitationally with the normal matter, but completely dominating the motion of the stars in a galaxy. What is this stuff? I will describe a direct search for Dark Matter in the laboratory using a bubble chamber as a nuclear recoil detector to look for both spin-dependent and spin-independent WIMP-nucleus scattering events. (Weakly Interacting Massive Particles [WIMPs] are the M~100 GeV/c2 particle physics hypothesis for the Dark Matter. The Lightest Supersymmetric Particle is the most obvious candidate.) The COUPP collaboration has built and operated a series of heavy liquid room temperature bubble chambers, of increasing size and sensitivity. This work has yielded best in the world limits on spin-dependent WIMP-nucleus scattering cross-sections. Data being taken now should allow us to become competitive with best in the world spin-independent measurements. This work is done with 2-4 Kg chambers. A 60Kg chamber is now being debugged. I will cover the Dark Matter problem and the current direct detection searches with an emphasis our recent work and prospects for progress in the near future.
Host: T-2, Vincenzo Cirigliano, 5-2829