1. Search for Cosmic Antiparticles First Workshop on Underground experiments and Astroparticle physics October 23, 2002 Eun-Suk Seo University of Maryland & Ewha Women’s University

2. Eun-Suk Seo, University of Maryland Discovery of Cosmic rays

3. Eun-Suk Seo, University of Maryland

4. BESS Spectrometer Thin Superconducting Solenoid enables ： Cylindrical Detector → Large Acceptance Uniform magnetic field→ Clear separation and High Resolution Antiproton and proton deflect oppositely in magnetic field Momentum Velocity -1 + - - +

5. Eun-Suk Seo, University of Maryland Searching for Antimatter Unlike antiprotons, anti-helium Unlike antiprotons, anti-helium cannot be produced by collisions in the interstellar gas above the level 10 -13 or so These 90% confidence limits on the ratio of anti- helium/helium in cosmic rays have been going down over the years These 90% confidence limits on the ratio of anti- helium/helium in cosmic rays have been going down over the years They are now below10 -6 and will be pushed to 10 -7 by longer BESS flightsThey are now below10 -6 and will be pushed to 10 -7 by longer BESS flights AMS-02 is expected to reach below 10 -9 AMS-02 is expected to reach below 10 -9

6. Eun-Suk Seo, University of Maryland If the Universe began with a Big Bang Half of the Universe is made out of matter Half is made out of antimatter Where is the Antimatter Universe?

7. Eun-Suk Seo, University of Maryland

8. Theories predicting the Existence of Antimatter The breakdown of the Time-Reversal symmetry in the early universe might have set different signs for the production of matter and antimatter in different regions of space Since there are 10 8 clusters of galaxies and the observational constraints are limited to the scale of the clusters, the universe can be symmetric on a larger scale The observed matter-antimatter asymmetry is then a local phenomenon

9. Eun-Suk Seo, University of Maryland The detection of one antihelium or anticarbon would have a profound impact on our understanding of the origin of symmetry in Time, which is the foundation of modern physics

10. Eun-Suk Seo, University of Maryland 90% of Universe is not observable It is made of Dark Matter What is Dark Matter?

11. Eun-Suk Seo, University of Maryland Dark Matter Most physicists believe that Weakly Interacting Massive Particle (WIMPS) comprise dark matter. This can be tested by direct search for various annihilating products of WIMP’s in the Galactic halo

12. Eun-Suk Seo, University of Maryland Detectors

13. Eun-Suk Seo, University of Maryland Antiprotons from Neutralino Annihilation?

14. Eun-Suk Seo, University of Maryland What do antiprotons tell us?

15. Eun-Suk Seo, University of Maryland Cosmic Ray “Solar” Modulation

16. Eun-Suk Seo, University of Maryland Randy Jokipii Views the Heliosphere ….

17. Eun-Suk Seo, University of Maryland

21. A smoking gun? Positrons from annihilating dark matter neutralinos. Secondary positrons produced from cosmic ray interactions with ISM

22. Eun-Suk Seo, University of Maryland Alpha Magnet Spectrometer AMS-02 Instrument Configuration. AMS Mounted on Full-truss Payload Site

23. Eun-Suk Seo, University of Maryland

24. Antiproton Measurement in 1993 - 2000 ( by BESS: KEK, NASA/GSFC, Tokyo, Kobe, Maryland, and ISAS) Aerogel Cherenkov Counter installed First Flight Antiproton Observation, Year-by-Year and Accumulated Northern-Canada Ballooning beyond Space Station Orbits

25. Eun-Suk Seo, University of Maryland Future Magnet Spectrometers BESS

26. Eun-Suk Seo, University of Maryland TIGER: a record setting 31 day flight Trans-Iron Galactic Element Recorder (TIGER) is to measure the abundance in the GCRs of each element from sulfur (atomic number, Z=16) through zirconium (Z=40). Launch on 12/21/01

27. Eun-Suk Seo, University of Maryland Long Duration Balloon Flights in Northern Hemisphere

28. Eun-Suk Seo, University of Maryland

29. Magnet Spectrometers