Search for Cosmic Antiparticles

First Workshop on Underground experiments and Astroparticle physics

October 23, 2002

Eun-Suk SeoUniversity of Maryland & Ewha Women’s University

Eun-Suk Seo, University of Maryland

Discovery of Cosmic rays

Eun-Suk Seo, University of Maryland

Eun-Suk Seo, University of Maryland

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

+-

- +

Eun-Suk Seo, University of Maryland

Searching for Antimatter

• Unlike antiprotons, anti-heliumUnlike antiprotons, anti-heliumcannot be produced by collisions cannot be produced by collisions in the interstellar gas above thein the interstellar gas above thelevel 10level 10-13-13 or so or so• These 90% confidence limits These 90% confidence limits on the ratio of on the ratio of anti-helium/helium in cosmic anti-helium/helium in cosmic rays have been going down over rays have been going down over the years the years •They are now below10They are now below10-6-6 and and will be pushed to 10will be pushed to 10-7-7 by longer by longer BESS flights BESS flights • AMS-02 is expected to reach AMS-02 is expected to reach below 10below 10-9-9

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 isthen 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

...

....

....

e

p

Eun-Suk Seo, University of MarylandDetectors

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-02 Instrument Configuration.

AMS Mounted on Full-truss Payload Site

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)

0

500

1000

1500

2000

2500

1993 1994 1995 1996 1997 1998 1999 2000 2001

Antiproton-Events-by-2000-t

each yearintegrated

Ant

ipro

ton

Eve

nts

Year

Aerogel Cherenkov Counter installed

First Flight

Antiproton Observation,Year-by-Year and Accumulated

Northern-Canada Ballooning beyond Space Station Orbits

Eun-Suk Seo, University of Maryland

Future Magnet Spectrometers

BESS

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

Eun-Suk Seo, University of Maryland

Long Duration Balloon Flights in Northern Hemisphere

Eun-Suk Seo, University of Maryland

600-ft tall(182.9m)

FURLEDPARACHUTE

WASHINGTONMONUMENT555.4-ft high

(169.3 meters)

90 ft (27.4m)

510 ft(155.5m)

200 ft(61m)

10 ft (3m)

810 ft(247m)

558 ft(170.1m)

348-ft tall(106.1-meter)

480 ft (146.3m)

FLIGHT TRAIN210 ft (64m)

BALLOON ENVELOPE PARAMETERS:

39.96 *10 6 feet 3

20.00 acres 0.8 mil 0.8 mil20.00 miles

- - - - Balloon Volume - - - - - - - - Amount of Material - - - - - - - - Skin Thickness - - - - -- - - - - Cap Thickness - - - - -- - - - Length of Seams - - - -

1.13 *10 6 meters 3

81.00 *10 3 meters 2

20.32 microns20.32 microns32.20 kilometers

BALLOON at FLOATALTITUDE ~ 126,000 ft (38.4 km)WEIGHT ~ 5,000 lbs (2267.6 kg)

BALLOON at LAUNCH

Eun-Suk Seo, University of Maryland

Magnet Spectrometers