Transcript Document 7617498

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
Discovery of Cosmic rays
Eun-Suk Seo, University of Maryland
Eun-Suk Seo, University of Maryland
BESS Spectrometer
Antiproton and proton deflect
oppositely in magnetic field
Velocity-1
-
-
+
+
Momentum
Thin Superconducting Solenoid enables：
•Cylindrical Detector → Large Acceptance
•Uniform magnetic field→ Clear separation and High Resolution
Eun-Suk Seo, University of Maryland
Searching for Antimatter
• 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 antihelium/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 flights
• AMS-02 is expected to reach
below 10-9
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?
Eun-Suk Seo, University of Maryland
Eun-Suk Seo, University of Maryland
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 108 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
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
Eun-Suk Seo, University of Maryland
90% of Universe is not
observable
It is made of Dark Matter
What is Dark Matter?
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
    p  ....
  ....

e  ...
Eun-Suk Seo, University of Maryland
Detectors
Eun-Suk Seo, University of Maryland
Antiprotons from Neutralino Annihilation?
Eun-Suk Seo, University of Maryland
What do antiprotons tell us?
Eun-Suk Seo, University of Maryland
Cosmic Ray “Solar” Modulation
Eun-Suk Seo, University of Maryland
Randy Jokipii Views the Heliosphere ….
Eun-Suk Seo, University of Maryland
Eun-Suk Seo, University of Maryland
Eun-Suk Seo, University of Maryland
Eun-Suk Seo, University of Maryland
Eun-Suk Seo, University of Maryland
A smoking gun?
Positrons from
annihilating dark
matter neutralinos.
Secondary positrons
produced from
cosmic ray
interactions with ISM
Eun-Suk Seo, University of Maryland
Alpha Magnet Spectrometer
AMS Mounted on Full-truss Payload Site
AMS-02 Instrument Configuration.
Eun-Suk Seo, University of Maryland
Eun-Suk Seo, University of Maryland
Antiproton Measurement in 1993 - 2000
(by BESS: KEK, NASA/GSFC, Tokyo, Kobe, Maryland, and ISAS)
Antiproton-Events -by-2000-t
2500
Northern-Canada Ballooning
2000
Antiproton Events
beyond Space Station Orbits
each year
integrated
Aerogel Cherenkov
Counter installed
1500
1000
First Flight
500
0
1993
1994
1995
1996
1997
1998
1999
2000
Year
Antiproton Observation,
Year-by-Year and Accumulated
Eun-Suk Seo, University of Maryland
2001
Future Magnet Spectrometers
BESS
Eun-Suk Seo, University of Maryland
TIGER: a record setting 31 day flight
Launch on 12/21/01
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).
Eun-Suk Seo, University of Maryland
Long Duration Balloon Flights in Northern Hemisphere
Eun-Suk Seo, University of Maryland
Eun-Suk Seo, University of Maryland
Magnet Spectrometers
Eun-Suk Seo, University of Maryland