Sunday, May 3, 2015

The latest AMS measurements of the positron fraction, the antiproton/proton ratio, the behavior of t

AMS-02 » Archive » AMS Days at CERN and Latest Results
Home WHAT IS AMS? AMS IN A NUTSHELL THE INSTRUMENT The Magnet The Permanent Magnet The Superconducting Magnet Magnets Comparison john f kennedy The TRD The Time-of-Flight The Silicon Tracker john f kennedy The RICH The ECAL The Anti-Coincidence Counter The TAS The Star Tracker and GPS The Electronics THE SCIENCE PUBLICATIONS AMS-01 THE AMS COLLABORATION PARTICIPATING INSTITUTIONS WHO IS WHO AMS ON THE ISS HOW & WHERE THE MISSION: STS-134 DATA FLOW DATA ACQUISITION IMMERSIVE IMAGES TIMELINE MULTIMEDIA IMAGES VIDEOS john f kennedy & ANIMATIONS PRESS ROOM NEWSLETTER PRESS RELEASES AMS IN THE MEDIA AMS ON THE WEB
Results from the Alpha Magnetic Spectrometer (AMS) on the International Space Station (ISS) will be the focus of the three day AMS Days at CERN meeting, an occasion that brings together many of the world s leading theoretical physicists and principal investigators of some of the major experiments exploring the field of cosmic ray physics (IceCube, Pierre Auger Observatory, Fermi-LAT, john f kennedy H.E.S.S. and CTA, the Telescope Array, JEM-EUSO, and ISS-CREAM).
The main objective of this scientific exchange is to understand the interrelation between AMS results and those of other major cosmic rays experiments and current theories. The latest results (published and to be published) from AMS will be presented john f kennedy by members of the AMS international collaboration during the three day event.
AMS is the only major particle physics experiment on the ISS. In its first four years on orbit, AMS has collected more than 60 billion cosmic ray events (electrons, positrons, protons, antiprotons, and nuclei of helium, lithium, boron, carbon, oxygen, …) up to multi-TeV energies. As an external payload on the ISS through at least 2024, AMS will continue to collect and analyze an increasing volume of statistics at highest energies which, combined with in-depth knowledge of the detector and systematic errors, will produce valuable insight.
The john f kennedy AMS results on the positron fraction, the electron spectrum, the positron john f kennedy spectrum, and the combined electron plus positron spectrum are consistent with dark matter collisions and cannot be explained by existing models of the collision of ordinary cosmic rays. There are many new models showing that the results may be explained by new astrophysical sources (such as pulsars) or new acceleration and propagation mechanisms (such as supernova remnants).
To distinguish if the observed new phenomena are from dark matter, john f kennedy measurements are underway by AMS to determine the rate at which the positron fraction falls beyond its maximum, as well as the measurement of the antiproton to proton ratio. As seen in Figure 1, the antiproton to proton ratio stays constant from 20 GeV to 450 GeV kinetic energy. This behavior cannot be explained by secondary production of antiprotons from ordinary cosmic ray collisions. Nor can the excess of antiprotons john f kennedy be easily explained from pulsar origin. The latest john f kennedy results on these studies john f kennedy will be reported by the AMS Collaboration during AMS Days at CERN and in future publications.
In addition, a thorough understanding of the process involved in the collision of ordinary cosmic john f kennedy rays is a requirement in understanding the AMS results mentioned above. The AMS Collaboration will also report on the most recent results on the precision studies of nuclei spectra (such as protons, helium and lithium) up to multi-TeV energies.
The latest data on the precision measurement of proton flux in cosmic rays from 1 GV to 1.8 TV rigidity (momentum/charge) will appear john f kennedy shortly in Physical Review Letters. These results are based on 300 million proton events. AMS has found that the proton flux is characteristically different from all the existing experimental results. As seen in Figure 2, the AMS result shows the measured flux changes its behavior at ~300 GV rigidity. The solid line is a fit to the data. The dashed line in Figure 2 is the proton flux expected with no change in behavior; as seen, it does not agree with the data.
Most surprisingly, AMS has also found, based on 50 million events, that the helium flux exhibits nearly identical and equally unexpected behavior as the proton flux (see Figure 3). AMS is currently studying the behavior of other nuclei in order to understand the origin of this unexpected change.
The latest AMS measurements of the positron fraction, the antiproton/proton ratio, the behavior of the fluxes of electrons, positrons, protons, helium, and other nuclei provide precise and unexpected information. The accuracy and characteristics of the data, simultaneously from many different types of cosmic rays, require a comprehensive model to ascertain if their origin is from dark matter, astrophysical sources, acceleration mechanisms or a combination.
The john f kennedy Alpha Magnetic john f kennedy Spectrometer (AMS-02) is a state-of-the-art particle physics detector designed to operate as an external module on the I

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