THE SCIENCE


“THE MOST EXCITING OBJECTIVE OF AMS IS TO PROBE THE UNKNOWN; TO SEARCH FOR PHENOMENA WHICH EXIST IN NATURE THAT WE HAVE NOT YET IMAGINED NOR HAD THE TOOLS TO DISCOVER”

(S.C.C. Ting)

Cosmos is the ultimate laboratory, where cosmic rays can be observed at energies higher than any accelerator. AMS-02, the first large magnetic spectrometer to be launched in orbit, will use the unique environment of space to advance the knowledge of the universe and to contribute to the understanding of its structure and origin by searching for the missing antimatter, by exploring the origin of dark matter and by measuring with the highest accuracy the composition of cosmic rays in the multi TeV region of energy. In addition, it will search for strangelets, a possible new form of matter made out the so-called strange quarks.
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Antimatter

Experimental evidence indicates that our galaxy is made of matter; however, there are more than 100 hundred million galaxies in the universe and the Big Bang theory assumes that equal amounts of matter and antimatter were present at the origin of the universe. Theories which try to explain the present matter antimatter asymmetry are not compatible with other measurements. Whether or not nuclear antimatter still exists in the universe is a fundamental question in modern astroparticle physics and cosmology. The observations of just one antihelium nucleus would provide evidence for the existence of large amount of antimatter somewhere in the universe. In 1998, AMS-01 established an upper limit of 10−6 for the antihelium/helium flux ratio in the universe. AMS-02 will reach a sensitivity of 10−9, three orders of magnitude better than AMS-01, hugely extending the volume of the Universe which can be tested for the existence of primordial antimatter.

.» In Depth: The Antimatter Academy at CERN

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“NEVER IN THE HISTORY OF SCIENCE WE WERE SO AWARE OF OUR IGNORANCE: WE KNOW THAT WE DO NOT KNOW ANYTHING ABOUT WHAT MAKES 95% OF OUR UNIVERSE”

(R. Battiston)

Credit: NASA / WMAP Science Team

 

Dark matter

The visible matter in the universe, such as stars, adds up to less than 5 percent of the total mass-energy balance of the universe. The other 95 percent is dark, either dark matter, which is estimated at 23 percent of the mass of the universe, or dark energy, which makes up the balance. The exact nature of both dark components is still unknown. One of the leading candidates for dark matter is the neutralino. If neutralinos exist, they could collide with each other producing excesses of charged or neutral particles which can be detected by AMS-02. Anomalous peaks or structures in the energy spectra of positron, anti-proton, or gamma ray could signal the existence of neutralinos or other dark matter candidates.

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Strangelets

Six types of quark (up, down, strange, charm, bottom and top) have been found experimentally, however all matter on Earth is made of only two types, up and down. It is a fundamental question whether there is matter made of three quarks (up, down and strange). Predicted theoretically such matter is known as strangelets. Strangelets can have extremely large mass and very small charge-to-mass ratios. It would be a totally new form of matter. During its operation on the ISS, AMS-02 might detect the existence of this exotic form of matter.

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Cosmic rays composition and fluxes

AMS-02 will be operative on the ISS for 10+ years, gathering a huge amount of data and determining long term variations of the cosmic rays fluxes and composition, from protons to iron, and over a wide energy range. These data will improve our understanding of the interstellar propagation and of the mechanisms at the origins of cosmic rays. In addition, accurately understanding cosmic radiation is required for manned interplanetary flight: for example, Galactic Cosmic Rays (GCR) represent a significant obstacle to a manned space flight to Mars, and accurate measurements of the flux and composition of primary cosmic rays are needed to plan appropriate countermeasures.