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Spin-Dependent Wimp Limits from a Bubble Chamber. E. Behnke,1 J. I. Collar,2 * P. S. Cooper,3 K. Crum,2 M. Crisler,3 M. Hu,3 I. Levine,1 D. Nakazawa,2 H. Nguyen,3 B. Odom,2 E. Ramberg,3 J. Rasmussen,2 N. Riley,2 A. Sonnenschein,3 M. Szydagis,2 R. Tschirhart3
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Spin-Dependent Wimp Limits from a Bubble Chamber • E. Behnke,1 J. I. Collar,2* P. S. Cooper,3 K. Crum,2 M. Crisler,3 M. Hu,3 I. Levine,1 D. Nakazawa,2 H. Nguyen,3 B. Odom,2 E. Ramberg,3 J. Rasmussen,2 N. Riley,2 A. Sonnenschein,3 M. Szydagis,2 R. Tschirhart3 • Science 15 February 2008:Vol. 319. no. 5865, pp. 933 - 936
Why? Why was this experiment done? Dark matter makes up 70% of the universe. We don’t know what dark matter is. It might be WIMP-proton scattering. Wimp-proton scattering is hard to detect. …………Do WIMPs even exist??
What to do? What did this experiment do? Exclude background radiation. Increase detection time to include WIMPs. Improve nuclear-recoil specific detection. Find WIMPs.
Spoiler: No WIMPs here.
Outline • WIMPs • Bubble Chambers • Bubble Chamber tweaking • For rate • For background • Data • Conclusions
Outline • WIMPs • Bubble Chambers • Bubble Chamber tweaking • For rate • For background • Data • Conclusions
Weakly-Interacting Massive Particles • Hypothetical super-symmetric partners • Not much known (mass, etc) • Like Heavy, Slow neutrinos. • Interacts with WNF and Gravity http://serenitythruhaiku.files.wordpress.com/2009/02/wimp.jpg Axino · Chargino · Gaugino · Gluino · Gravitino · Higgsino · Neutralino · Sfermion
Outline • WIMPs • Bubble Chambers • Bubble Chamber tweaking • For rate • For background • Data • Conclusions
http://maltwood.uvic.ca/physics/Libraries/imagelibrary/29-52low.jpghttp://maltwood.uvic.ca/physics/Libraries/imagelibrary/29-52low.jpg http://en.wikipedia.org/wiki/Bubble_chamber http://beer.thetazzone.com/images/drinkBeer9.jpg
Outline • WIMPs • Bubble Chambers • Bubble Chamber tweaking • For rate • For background • Data • Conclusions
“deactivate inhomogeneous bubble nucleation centers “ Instead of few milliseconds, ‘indefinite’. • - Good for WIMP rate of 1/kg*day • worst case scenario: < 1/ton*year Tuned to detect only particles of large stopping power (dE/dx>50keV/um) - slow and big) Just like WIMPs
High (60C) • Moderate (30C)- High dE/dx only (222Rn a-decay) • WIMP
Outline • WIMPs • Bubble Chambers • Bubble Chamber tweaking • For rate • For background • Data • Conclusions
Outline • WIMPs • Bubble Chambers • Bubble Chamber tweaking • For rate • For background • Data • Conclusions
References • Spin-Dependent WIMP Limits from a Bubble Chamber • E. Behnke, J. I. Collar, P. S. Cooper, K. Crum, M. Crisler, M. Hu, I. Levine, D. Nakazawa, H. Nguyen, B. Odom, E. Ramberg, J. Rasmussen, N. Riley, A. Sonnenschein, M. Szydagis, and R. Tschirhart (15 February 2008)Science319 (5865), 933. • Wikiedia.com • G. Jungman, M. Kamionkowski, K. Griest, Phys. Rep.267, 195 (1996). • C. Rubbia, Nucl. Phys. B Proc. Suppl.36, xvii (1994).