1. DARK MATTER IN THE UNIVERSE? PRESENTED BY L. KULL AT THE R.H.FLEET SCIENCE CENTER December 14,2005

2. Why be concerned about the amount of matter in the universe? Start with Einstein’s Field Equations (they describe the relationship between energy density and the curvature of the universe). Start with Einstein’s Field Equations (they describe the relationship between energy density and the curvature of the universe). Use the Robertson-Walker metric to describe the geometry of space/time (curved?) within these equations (this metric also allows a description of a space which expands with time). Use the Robertson-Walker metric to describe the geometry of space/time (curved?) within these equations (this metric also allows a description of a space which expands with time). The result is the Friedmann Equation – today a popular mathematical description of an expanding universe. The result is the Friedmann Equation – today a popular mathematical description of an expanding universe. This equation provides an important descriptive parameter, a “critical energy density” directly related to a “flat” universe which expands (asymptotically) forever. This equation provides an important descriptive parameter, a “critical energy density” directly related to a “flat” universe which expands (asymptotically) forever. Could most or all of this energy density be provided by matter? If so, what form of matter? Could most or all of this energy density be provided by matter? If so, what form of matter?

3. Einstein’s Field Equations – A Link Between Physics and Geometry

4. Geometry – The Robertson Walker (R-W) Line Element

5. Critical Density from Friedmann Equation

6. The mass density of visible matter (stars)

7. The mass of those forms of invisible matter we know something about. Gas clouds (ionized and neutral) In our galaxy ~1/10 of the star mass. In the Coma galaxy cluster~6 times the star mass. Gas clouds (ionized and neutral) In our galaxy ~1/10 of the star mass. In the Coma galaxy cluster~6 times the star mass. Planets, asteroids, dust. Planets, asteroids, dust. MACHOs Massive Compact Halo Objects (black holes, neutron stars, dwarfs) - to be discussed. MACHOs Massive Compact Halo Objects (black holes, neutron stars, dwarfs) - to be discussed. Neutrinos –to be discussed. Neutrinos –to be discussed.

8. Measuring the mass of MACHOs (Massive Compact Halo Objects)

9. Estimates of the mass of neutrinos in the universe.

10. A Model for the Determination of the Baryon Energy Density of the Universe

11. Calculated Results from the Model

12. The Baryon Density of the Universe

13. Orbital Velocity of Stars and Gas around Galaxies – best evidence for DARK MATTER

14. Dark Matter Detection Problem – Big Picture

15. Dark Matter Detection Problem – Small Picture

16. Detection Mechanisms for Nuclear Recoil Energy Depositions

17. Problem: very small signal and VERY LARGE BACKGROUNDS Backgrounds cosmic rays and secondary particles (neutrons) cosmic rays and secondary particles (neutrons) detector impurities (radioactive and non) detector impurities (radioactive and non) thermal noise thermal noise ambient natural radiation (gamma and neutron) ambient natural radiation (gamma and neutron) Low Background Design Features underground locations (deep mines) exterior shielding (passive and active) ultra pure detector material detector cooling (cryogenic levels)

18. DAMA Detecror Target material: NaI Total target mass: 100 kg Operating temp: ambient Location: Gran Sasso, Italy

19. DAMA Data – no confirming data from other experiments - (???)

20. CDMS Detector Target material: Ge/Si (100g/250g) crystals Target material: Ge/Si (100g/250g) crystals Total target mass:7 kg Total target mass:7 kg Operating temp: 0.01K Operating temp: 0.01K Location: Soudan Mine, USA Location: Soudan Mine, USA

21. ZEPLIN II Detector Target material: Xe (l & g) Target material: Xe (l & g) Total target mass: 30 kg Total target mass: 30 kg Operating temp : ~3K Operating temp : ~3K Location: Boulby Mine, UK Location: Boulby Mine, UK

22. Dark Matter Detection Experiments and Collaborations

23. Current Estimated Detection Limits

24. Detection Techniques vs. Experiments/Collaborations