XXXVI th Recontres de Moriond Very High Energy Phenomena in the Universe 24 January 2001 Dan Javorsek, Ephraim Fischbach, Dave Elmore, and Tom Miller Purdue University, West Lafayette, IN Doug Oliver and Vigdor Teplitz Southern Methodist University, Dallas, TX New Experimental Limits on the Existence of Strongly Interacting Dark Matter Particles

24 January 2001Purdue University Department of Physics Overview What is a SIMP? Motivations for SIMPs –The Dark Matter Problem –Ultra High Energy Cosmic Rays –Lightest Supersymmetric Particle Our Experiment First Results Future Work

24 January 2001Purdue University Department of Physics SIMPs Strongly Interacting Massive Particles –Neutral Particle –Mass > 1 GeV/c 2 M proton  1 GeV –Bound by the strong force to a massive (high Z) stable atom (Au) SIMPs may manifest as an anomalous isotope Recent developments in particle physics and cosmology prompts searches for superheavy particles Au X

24 January 2001Purdue University Department of Physics Motivation: Dark Matter Starkmann et al., Phys. Rev. D 41,3594 (1990) Mohapatra & Teplitz, PRL 81, 3079 (1998) –If :  ss ~ 1/M s –Then : SIMPs can have sufficient abundance to saturate the cosmic density or galactic halo SIMPs masses needed to saturate –Cosmic density M S > GeV –Galactic halo M S < 100 GeV

24 January 2001Purdue University Department of Physics Motivation: UHECR Ultra High Energy Cosmic Rays (UHECRs) Lose energy scattering with the cosmic background radiation (GZK) To date, we have more than 700 confirmed events above the GZK cutoff (10 19 eV) Models of Albuquerque, Farrar, and Kolb suggest [Phys. Rev. D 59, (1998)] 10 GeV/c 2 < M S < 50 GeV/c 2

24 January 2001Purdue University Department of Physics Motivation: SUSY Mohapatra & Nandi, PRL 79, 181 (1997) Chacko et al., Phys. Rev. D56, 5466 (1997) Raby, Phys. Rev. D 56, 2852 (1997) –suggest the gluino is the lightest supersymmetric particle (LSP) TheoryPredicted SIMP Mass Dark MatterM S < 100 GeV Ultra High Energy Cosmic Rays10 GeV < M S < 50 GeV Lightest SUSY Particle6.3 GeV < M S < 100 GeV

24 January 2001Purdue University Department of Physics The Experiment Use Accelerator to search for anomalously heavy isotopes of Au

24 January 2001Purdue University Department of Physics Results Scanned SIMP mass range from GeV/c 2 Scanned both lab gold and Australian gold Calculated the abundance of Au nuclei with SIMPs to those without

24 January 2001Purdue University Department of Physics Results M’ = effective SIMP mass = M X -M Au = M S -|E B | M X ’ = 3 GeV50 GeV100 GeV144 GeV X/Au < 1.3  < 1.0  < 4.3  < 4.4 

24 January 2001Purdue University Department of Physics Results Mohapatra et al., Phys. Rev. D 60, (1999)  SN (mb) M X (GeV)

24 January 2001Purdue University Department of Physics Geological Samples Western Australia –15 cm of surface using a metal detector –Exposure age  50 million years Northwestern Arizona –Mineral Park District (Gold Basin) –Exposure age  5 million years Western North Carolina –Collected from streams in the Appalachians –South of glaciated area affected by the Ice Age –Deposits formed  570 million years ago

24 January 2001Purdue University Department of Physics Exotic Samples Long Duration Exposure Facility (LDEF) –Part of the Meteoroid and Exposure Module –Exposed to space from 1984 to 1990 –Performed 32,422 Earth orbits –Experienced ½ a solar cycle Iron Meteorite Beam dump from Brookhaven National Laboratory

24 January 2001Purdue University Department of Physics Conclusions SIMP abundance must be less than 1 x Future Work –Increase mass scan range (up to 1 TeV/c 2 ) –Include more diverse samples LDEF, Brookhaven, Meteorite, Arizona, NC, Dentists & Jewlers –Search in Lead and Uranium