Low Radioactivity NaI for Dark Matter Studies

Dark Matter accounts for nearly 90 percent of all matter in the universe, yet its identity remains one of the biggest mysteries of modern science. Although Dark Matter is invisible to telescopes, astronomers know it is there from the gravitational influence it exerts over galaxies. Using sensitive low background detectors, such as low-background germanium or NaI(Tl), several research groups at the Soudan Underground Laboratory in Soudan, MN and at the Gran Sasso National Laboratory in Italy, are carrying out experiments to search for rare collisions of the dark matter particles with ordinary matter. The collisions are detected by observing the recoiling nuclei that result from the collisions of dark matter particles with ordinary nuclei in the detector. The Gran Sasso experiments have shown enticing results that require further explanation. By setting up a new NaI experiment with lower background levels, the test measurements would have a higher sensitivity that could confirm or refute the DAMA/LIBRA results at Gran Sasso. The goal of the proposed Phase I and Phase II projects is to investigate higher purity NaI scintillation materials that promise higher sensitivity and reduced errors due to lower background fromK-contamination. Commercial Applications and Other Benefits: Over and above use in Dark Matter experiments, the new detectors will be commercially applicable to medical imaging, NDE, and materials analysis. They will also be useful in nuclear, high energy and space physics experiments