XXXVIth Recontres de MoriondVery High Energy Phenomena in the Universe

24 January 2001

Dan Javorsek, Ephraim Fischbach, Dave Elmore, and Tom Miller

Purdue University, West Lafayette, IN 47907

Doug Oliver and Vigdor TeplitzSouthern Methodist University,

Dallas, TX 75275

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/c2 Mproton 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

AuX

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/Ms

– Then : SIMPs can have sufficient abundance to saturate the cosmic density or galactic halo

• SIMPs masses needed to saturate– Cosmic density

MS > 103.5 GeV– Galactic halo

MS < 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 (1019 eV)

• Models of Albuquerque, Farrar, and Kolb suggest [Phys. Rev. D 59, 015021 (1998)]

10 GeV/c2 < MS < 50 GeV/c2

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)

Theory Predicted SIMP Mass

Dark Matter MS < 100 GeV

Ultra High Energy Cosmic Rays

10 GeV < MS < 50 GeV

Lightest SUSY Particle6.3 GeV < MS < 100

GeV

24 January 2001Purdue University Department of Physics

TandemAccelerator

Analyzing andSwitching Magnets

Ion Source Injector MagnetGasIonizationDetector

ElectrostaticAnalyzer

The Experiment

• Use Accelerator to search for anomalously heavy isotopes of Au

24 January 2001Purdue University Department of Physics

Results

• Scanned SIMP mass rangefrom 2.8-144 GeV/c2

• Scanned both lab gold and Australian gold

• Calculated the abundance of Au nuclei with SIMPs to those without

X

Aux I

q

Au

X

det

12 )ln)(10672.2(

24 January 2001Purdue University Department of Physics

Results

0 50 100 15010

-11

10-10

10-9

MX [GeV/c2]

X/A

u

M’ = effective SIMP mass

= MX-MAu

= MS-|EB|

MX’ = 3 GeV 50 GeV 100 GeV 144 GeV

X/Au < 1.3 10-11 < 1.0 10-10 < 4.3 10-10 < 4.4 10-10

24 January 2001Purdue University Department of Physics

ResultsMohapatra et al., Phys. Rev. D 60, 115013 (1999)

SN(mb)

MX (GeV)

0.0005

0.0015

0.0042

0.012 0.032 0.09 0.25 0.69 1.9 5.3

2.7 5.9 7.9 8.3

4.3 5.7 7.7 8.1 11.1

7.1 5.5 7.5 7.9 10.9 12.1

12 5.6 7.6 8.1 8.5 12.2 12.7

19 7.5 7.9 8.3 11.3 12.5 12.9

31 7.4 7.8 8.2 8.6 12.4 12.8 13.2

50 5.7 7.7 8.1 8.5 11.5 12.7 13.1 13.6

81 5.7 7.7 8.1 8.5 8.9 11.9 13.1 13.5 14.0

132 5.7 7.7 8.1 8.5 8.9 9.3 12.2 13.5 13.9 14.3

220 6.0 8.0 8.4 8.9 9.3 9.7 12.6 13.9 14.3 14.7

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 10-11

• Future Work– Increase mass scan range (up to 1

TeV/c2)– Include more diverse samples

• LDEF, Brookhaven, Meteorite, • Arizona, NC, Dentists & Jewlers

– Search in Lead and Uranium