Alpha Magnetic Spectrometer - 02 (AMS-02) - 12.10.14

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Science Objectives for Everyone
Stars, planets and the molecules that make them are only about five percent of the total mass in the universe — the rest is either dark matter or dark energy, but no one has ever seen this material or been able to study it. What’s more, the Big Bang theory holds that the universe should be made of equal parts matter and antimatter, but scientists have never detected naturally occurring antimatter. The Alpha Magnetic Spectrometer - 02 looks for evidence of these mysterious substances, along with very high-energy radiation coming from distant stars that could harm crewmembers traveling to Mars.

Science Results for Everyone
Information Pending

The following content was provided by Samuel C. Ting, Ph.D., Martin Pohl, Manuel Aguilar-Benitez, Silvie Rosier-Lees, Ph.D., Roberto Battiston, Shih-Chang Lee, Stefan Schael, and is maintained in a database by the ISS Program Science Office.

Experiment Details


Principal Investigator(s)

  • Samuel C. Ting, Ph.D., Massachusetts Institute of Technology, Cambridge, MA, United States
  • Martin Pohl, Departement de Physique, Université de , Genève, Switzerland
  • Manuel Aguilar-Benitez, Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Madrid, Spain
  • Silvie Rosier-Lees, Ph.D., Laboratoire d’Annecy-Le-Vieux de Physique des Particules and Universite de Savoie, Annecy-Le-Vieux, France
  • Roberto Battiston, Istituto Nazionale di Fiscica Nucleare-Sezione di Perugia and Universita di Perugia, Perugia, Italy
  • Shih-Chang Lee, Academia Sinica, Taipei, Taiwan
  • Stefan Schael, Physikalisches Institut B, Aachen, Germany

  • Co-Investigator(s)/Collaborator(s)
    Information Pending
    Developer(s) China
    Shandong University, Tsinan, , China

    Southeast University, Nanjing, , China

    Sun Yat-Sen University, School of Physics and Engineering, Guangzhou, , China

    Institute of Electrical Engineering (IEE), Beijing, , China

    Institute of High Energy Physics, Beijing, , China

    Jiao Tong University, Department of Physics, Shanghai, , China
    Aarhus University, Institute of Physics and Astronomy, Aarhus, , Denmark
    University of Turku, Space Research Laboratory, Turku, , Finland

    Helsinki University of Technology, Metsähovi Radio Observatory, Kylmala, , Finland
    Universite Joseph Fourier (Grenoble 1), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), , , France

    Université Montpellier II, Laboratoire de Physique Theorique and Astroparticules (LPTA), , , France

    Institut National de Physique Nucléaire et de Physique des Particules (IN2P3), , , France

    Laboratoire d'Annecy-le-Vieux de Physique des Particules (LAPP), Annecy-Le-Vieux, , France
    Rheinisch-Westfälische Technische Hochschule (RWTH), I. Physikalisches Institut (B), Aachen, , Germany
    In addition, the following Institutes/Groups made important contribution to the construction of the AMS-02 experiment:
    Max Planck Institute for Extraterrestrial Physics, Garching, , Germany
    Contributing Space Agencies
    German Aerospace Center (DLR), Cologne, , Germany
    Karlsruhe Institut fur Technologie (KIT), Universität Karlsruhe, Karlsruhe, , Germany
    Sezione INFN and Dipartimento di Fisica, Università degli Studi di Bologna, Bologna, Bologna, , Italy

    Sezione INFN and Dipartimento di Fisica, Universita degli Studi di Milano-Bicocca, Milano, , Italy

    Sezione INFN and Dipartimento di Fisica, Universita degli Studi di Perugia, Perugia, , Italy

    Sezione INFN and Dipartimento di Fisica, Universita degli Studi di Pisa, Pisa, , Italy

    Sezione INFN and Dipartimento di Fisica, Universita degli Studi di Roma 'La Sapienza', Roma, , Italy

    Dipartimento di Fisica, Universita degli Studi di Siena, Siena, , Italy

    Istituto di Ricerca sulle Onde Elettromagnetiche, IROE, CNR, Firenze, , Italy
    Contributing Space Agencies
    Italian Space Agency (ASI), Rome, , Italy
    Laboratorio SERMS, Polo Universitario di Terni, Terni, , Italy
    Universidad Nacional Autonoma (UNAM), Instituto de Ciencias Nucleares, Mexico City, , Mexico
    In addition, the following Institutes/Groups made important contribution to the construction of the AMS-02 experiment:
    Nationaal Instituut voor Subatomaire Fysica (NIKHEF), Amsterdam, , Netherlands
    Contributing Space Agencies
    European Space Agency (ESA), Noordwijk, , Netherlands
    The Netherlands
    Nationaal Lucht- en Ruimtevaartlaboratorium (NLR), Emmeloord, , Netherlands
    Dep. de Fisica Universidade de Coimbra, Coimbra, , Portugal

    Laboratorio de Instrumentacao e Fisica Experimental de Particulas (LIP), Lisbon, , Portugal
    University of Bucharest, Bucharest-Magurele, Romania, , Romania
    Russian Academy of Sciences, Moscow, , Russia

    I. V. Kurchatov Institute of Atomic Energy, Moscow, , Russia

    ITEP Institute for Theoretical and Experimental Physics (ITEP), Moscow, , Russia

    M.V. Lomonosov Moscow State University, Institute of Nuclear Physics, Moscow, , Russia
    South Korea
    Kyungpook National University, Daegu, , South Korea

    Ewha Women's University, Seoul, , South Korea
    Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid, , Spain

    Institute of Astrophysics of the Canary Islands (IAC), La Laguna, , Spain
    Departement de Physique, Université de Genève, Geneve, , Switzerland

    Eidgenossische Technische Hochschule Zurich (ETHZ), Zurich, , Switzerland
    Contributing Space Agencies
    European Center for Nuclear Research (CERN), Geneva, , Switzerland
    In addition, the following Institutes/Groups made important contribution to the construction of the AMS-02 experiment:
    Aerospace Industrial Development Corporation (AIDC), Taichung, , Taiwan
    Chung Shan Institute of Science and Technology (CSIST), Lungtan, , Taiwan

    Academia Sinica, Institute of Physics, Taipei, , Taiwan

    National Central University (NCU), Taipei, , Taiwan
    Contributing Space Agencies
    National Space Organization, HsinChu, , Taiwan
    National Taiwan University (NTU), Taipei, , Taiwan
    In addition, the following Institutes/Groups made important contribution to the construction of the AMS-02 experiment:
    Texas A&M University, Department of Physics, College Station, TX, United States

    Jacobs Sverdrup Engineering and Science Contract Group (ESCG), Houston, TX, United States
    Contributing Space Agencies
    National Aeronautics and Space Administration, Johnson Space Center, Houston, TX, United States
    United States
    Massachusetts Institute of Technology, Cambridge, MA, United States

    University of Maryland, Institute for Physical Science and Technology (IPST), College Park, MD, United States
    In addition, the following Institutes/Groups made important contribution to the construction of the AMS-02 experiment:
    Johns Hopkins University, Baltimore, MD, United States
    Contributing Space Agencies
    National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, MD, United States

    National Aeronautics and Space Administration, Kennedy Space Center, Cape Canaveral, FL, United States

    United States Department of Energy, Washington, DC, United States
    United States
    Yale University, Physics Department, New Haven, CT, United States
    Contributing Space Agencies
    National Aeronautics and Space Administration, Marshall Space Flight Center, Huntsville, AL, United States

    Sponsoring Space Agency
    National Aeronautics and Space Administration (NASA)

    Sponsoring Organization
    National Laboratory - Department of Energy (NL-DOE)

    Research Benefits
    Information Pending

    ISS Expedition Duration
    March 2011 - Ongoing

    Expeditions Assigned

    Previous ISS Missions
    The precursor to AMS-02, AMS, was flown on STS-91 in 1998. During this precursor flight, the basic technology required to perform the measurements was proven.

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    Experiment Description

    Research Overview

    • The Alpha Magnetic Spectrometer - 02 (AMS-02) is a high profile space-based particle physics experiment.

    • Orbiting the Earth at an altitude of 200 nautical miles attached to the International Space Station (ISS), AMS-02 will pioneer a new frontier in particle physics research.

    • As the largest and most advanced magnetic spectrometer in space, AMS-02 will collect information from cosmic sources emanating from stars and galaxies millions of light years beyond the Milky Way.


    Excerpt from "Alpha Magnetic Spectrometer - A Physics Experiment on the International Space Station" by Dr. Sam Ting: The Alpha Magnetic Spectrometer (AMS-02) is a state-of-the-art particle physics detector constructed, tested and operated by an international team composed of 60 institutes from 16 countries and organized under United States Department of Energy (DOE) sponsorship. The AMS-02 will use the unique environment of space to advance knowledge of the universe and lead to the understanding of the universe's origin by searching for antimatter, dark matter and measuring cosmic rays.

    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 of the origin of the universe requires equal amounts of matter and antimatter. Theories that explain this apparent asymmetry violate other measurements. Whether or not there is significant antimatter is one of the fundamental questions of the origin and nature of the universe. Any observations of an antihelium nucleus would provide evidence for the existence of antimatter. In 1999, AMS-01 established a new upper limit of 10-6 for the antihelium/helium flux ratio in the universe. AMS-02 will search with a sensitivity of 10-9, an improvement of three orders of magnitude, sufficient to reach the edge of the expanding universe and resolve the issue definitively.

    The visible matter in the universe (stars) adds up to less than 5 percent of the total mass that is known to exist from many other observations. The other 95 percent is dark, either dark matter (which is estimated at 20 percent of the universe by weight or dark energy, which makes up the balance). The exact nature of both still is unknown. One of the leading candidates for dark matter is the neutralino. If neutralinos exist, they should be colliding with each other and giving off an excess of charged particles that can be detected by AMS-02. Any peaks in the background positron, anti-proton, or gamma flux could signal the presence of neutralinos or other dark matter candidates.

    Six types of quark (u, d, s, c, b and t) have been found experimentally, however all matter on Earth is made up of only two types of quarks (u and d). It is a fundamental question whether there is matter made up of three quarks (u, d and s). This 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. AMS will provide a definitive answer on the existence of this extraordinary matter. The above three examples indicates that AMS will probe the foundations of modern physics.

    Cosmic radiation is a significant obstacle to a manned space flight to Mars. Accurate measurements of the cosmic ray environment are needed to plan appropriate countermeasures. Most cosmic ray studies are done by balloon-borne satellites with flight times that are measured in days; these studies have shown significant variations. AMS-02 will be operative on the ISS for a nominal mission of 3 years, gathering an immense amount of accurate data and allowing measurements of the long term variation of the cosmic ray flux over a wide energy range, for nuclei from protons to iron. After the nominal mission, AMS-02 can continue to provide cosmic ray measurements. In addition to the understanding the radiation protection required for manned interplanetary flight, this data will allow the interstellar propagation and origins of cosmic rays to be pinned down.

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    Space Applications

    High-energy radiation from distant stars and galaxies rains down on Earth constantly, but Earth’s atmosphere and powerful magnetic fields guard against them. Crewmembers traveling to Mars or other destinations are not protected from these cosmic rays, which can be harmful to human health. Understanding where cosmic rays come from and how they move through space can improve safety precautions for future manned missions.

    Earth Applications

    Similar to particle detectors on Earth, AMS-02’s core is a massive magnet that bends incoming charged particles from space; the direction they bend reveals if their charge is positive or negative.  This data combined with other measurements of mass and energy help scientist determine exactly what kind of particle passed through the detector.  That combined data can tell physicists about their origins. Earth’s atmosphere has a large effect on these cosmic particles, so a space-based observatory is essential to help answer fundamental physics questions that are difficult to study here on Earth.  Essentially, the Universe is the ultimate particle accelerator and is far better than any accelerator scientist will ever build on the Earth.  The detector also might reveal new particles and atomic nuclei that could provide evidence of dark matter or antimatter. Antimatter has been produced in Earth laboratories, but it has been elusive in the cosmos.

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    Operational Requirements

    AMS-02 will collect data 24 hours a day, 7 days a week, and 365 days a year. As long as the experiment has power provided by the ISS, the detectors will be on and measuring data at a rate of 7 Gigabits per seconds. This is equivalent to filling a 1 Gigabyte USB memory stick every second! Using sophisticated filtration and compression techniques, the advanced 600 computer processors located on AMS-02 are able to reduce the amount of data down by a factor of 3000. This data is sent from the ISS to the ground where researchers around the globe will compile and analyze data.

    Operational Protocols

    The AMS-02 will be launched on the Space Shuttle to the ISS on mission ULF6. AMS-02 will be mounted to the ISS S3 Upper Inboard Payload Attach Site during and extravehicular activity (EVA).

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    Results/More Information

    The Alpha Magnetic Spectrometer-02 (AMS-02) was installed on the International Space Station (ISS) on May 19, 2011. After 40 months of operations in space, AMS has collected 57 billion cosmic ray events. To date 41 billion have been analyzed. Of these, 9 million have been identified as electrons or positrons (an antimatter particle with the mass of an electron but a positive charge) in the energy range between 0.5 giga-electron volt (GeV) and 350 GeV. These events are used to determine the positron fraction - the ratio of positrons to the sum of electrons and positrons. Results show that below 10 GeV, the positron fraction decreased with increasing energy as predicted from events produced from cosmic ray collisions with the interstellar medium. However, the positron fraction increased steadily from 10 GeV to 250 GeV. This increase, previously recorded with less precision by instruments such as the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) and the Fermi Gamma-ray Space Telescope, conflicts with the standard theory of the positron fraction and indicates the existence of an unidentified source of positrons, such as pulsars or the annihilation of dark matter particles. A definitive indication of a dark matter signal has not yet been found.  Furthermore, researchers observed an unexpected decrease in slope from 20 GeV to 250 GeV. Current measurements extend the energy range to 500 GeV, and the latest data set shows that, above ∼200 GeV, the positron fraction is no longer increasing. This behavior of the positron fraction was previously unobserved. The reason for this plateau can only be ascertained by continuing to collect data up to the tera-electron volt (TeV) region and by measuring the antiproton to proton ratio to high energies. Also, the isotropies, that is, characteristic arrival directions, versus energy among the high-energy positrons and cosmic ray electrons suggests that they may come from different sources.

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    Results Publications

      Accardo L, Aguilar-Benitez M, Aisa D, Alpat B, Alvino A, Ambrosi G, Andeen K.  High statistics measurement of the positron fraction in primary cosmic rays of 0.5–500 GeV with the Alpha Magnetic Spectrometer on the International Space Station. Physical Review Letters. 2014 September 18; 113(12): 121101. DOI: 10.1103/PhysRevLett.113.121101.

      Aguilar-Benitez M, Alberti G, Alpat B, Alvino A, Ambrosi G, Andeen K, Anderhub H, Arruda MF, Azzarello P, Bachlechner A, Barao F, Baret B, Aurelien B, Barrin L, Bartoloni , Basara L, Basili A, Batalha L, Bates JR, Battiston R, Bazo J, Becker R, Becker UJ, Behlmann M, Beischer B, Berdugo J, Berges P, Bertucci B, Bigongiari G, Biland A, Bindi V, Bizzaglia S, Boella G, de Boer W, Bollweg KJ, Bolmont J, Borgia B, Borsini S, Boschini MJ, Boudoul G, Bourquin M, Brun P, Buenerd M, Burger J, Burger WJ, Cadoux F, Cai X, Capell M, Casadei D, Casaus J, Cascioli V, Castellini G, Cernuda I, Cervelli F, Chae M, Chang YH, Chen A, Chen C, Chen H, Cheng G, Chen HS, Cheng L, Chernoplyiokov N, Chikanian A, Choumilov E, Choutko V, Chung CH, Clark CS, Clavero R, Coignet G, Commichau V, Consolandi C, Contin A, Corti C, Costado Dios MT, Coste B, Crespo D, Cui Z, Dai M, Delgado C, Della Torre S, Demirkoz B, Dennett P, Derome L, Di Falco S, Diao XH, Diago A, Djambazov L, Diaz C, von Doetinchem P, Du WJ, Dubois JM, Duperay R, Duranti M, D'Urso D, Egorov A, Eline A, Eppling F, Eronen T, vanEs J, Esser H, Falvard A, Fiandrini E, Fiasson A, Finch E, Fisher P, Flood K, Foglio R, Fohey MF, Fopp S, Fouque N, Galaktionov Y, Gallilee MA, Gallin-Martel L, Gallucci G, Garcia B, Garcia J, Garcia-Lopez R, Garcia-Tabares L, Gargiulo C, Gast H, Gebauer I, Gentile S, Gervasi M, Gillard W, Giovacchini F, Girard L, Goglov P, Gong J, Goy-Henningsen C, Grandi D, Graziani M, Grechko A, Gross A, Guerri I, de la Guia C, Guo KH, Habiby M, Haino S, Hauler F, He ZH, Heil M, Heilig JA, Hermel R, Hofer H, Huang Z, Hungerford WJ, Incagli M, Ionica M, Jacholkowska A, Jang WY, Jinchi H, Jongmanns M, Journet L, Jungermann L, Karpinski W, Kim G, Kim K, Kirn T, Kossakowski R, Koulemzine A, Kounina O, Kounine A, Koutsenko V, Krafczyk M, Laudi E, Laurenti G, Lauritzen CA, Lebedev A, Lee MW, Lee S, Leluc C, Leon Vargas H, Lepareur V, Li J, Li Q, Li TX, Li W, Li Z, Lipari P, Lin CH, Liu D, Liu H, Lomtadze T, Lu Y, Lucidi S, Lubelsmeyer K, Luo JZ, Lustermann W, Lv S, Madsen J, Majka R, Malinin A, Mana C, Marin J, Martin TD, Martinez G, Masciocchi F, Masi N, Maurin D, McInturff A, McIntyre P, Menchaca-Rocha A, Meng Q, Menichelli M, Mereu I, Millinger M, Mo DC, Molina M, Mott PB, Mujunen A, Natale S, Nemeth PJ, Ni JQ, Nikonov N, Nozzoli F, Nunes P, Obermeier A, Oh S, Oliva A, Palmonari F, Palomares C, Paniccia M, Papi A, Park W, Pauluzzi M, Pauss F, Pauw A, Pedreschi E, Pensotti S, Pereira R, Perrin E, Pessina G, Pierschel G, Pilo F, Piluso A, Pizzolotto C, Plyaskin V, Pochon J, Pohl M, Poireau V, Porter SV, Pouxe J, Putze A, Quadrani L, Qi X, Rancoita PG, Rapin D, Ren Z, Ricol JS, Riihonen E, Rodriguez I, Roeser U, Rosier-Lees S, Rossi L, Rozhkov A, Rozza D, Sabellek A, Sagdeev R, Sandweiss J, Santos B, Saouter P, Sarchioni M, Schael S, Schinzel D, Schmanau M, Schwering G, Schulz von Dratzig A, Scolieri G, Seo E, Seo E, Shan BS, Shi JY, Shi YM, Siedenburg T, Siedling R, Son D, Spada F, Spinella F, Steuer M, Stiff K, Sun W, Sun W, Sun XH, Tacconi M, Tang CP, Tang XW, Tang Z, Tao L, Tassan-Viol J, Ting SC, Ting S, Titus C, Tomassetti N, Toral F, Torsti J, Tsai JR, Tutt JC, Ulbricht J, Urban TJ, Vagelli V, Valente E, Vannini C, Valtonen E, Vargas Trevino M, Vaurynovich S, Vecchi M, Vergain M, Verlaat B, Vescovi C, Vialle JP, Viertel G, Volpini G, Wang D, Wang NH, Wang QL, Wang R, Wang X, Wang ZX, Wallraff W, Weng Z, Willenbrock M, Wlochal M, Wu H, Wu KY, Wu Z, Xiao WJ, Xie S, Xiong R, Xin GM, Xu NS, Xu W, Yan Q, Yang J, Yang M, Ye QH, Yi H, Yu Y, Yu Z, Zeissler S, Zhang JG, Zhang Z, Zhang M, Zhuang ZM, Zhuang H, Zhukov VE, Zhukov VE, Zichichi A, Zuccon P, Zurbach C.  First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5-350 GeV. Physical Review Letters. 2013 Apr 3; 110: 141102-1 - 141102-10. DOI: 10.1103/PhysRevLett.110.141102.

      Aguilar-Benitez M, Aisa D, Alvino A, Ambrosi G, Andeen K, Arruda MF.  Electron and positron fluxes in primary cosmic rays measured with the Alpha Magnetic Spectrometer on the International Space Station. Physical Review Letters. 2014 September 18; 113(12): 121102. DOI: 10.1103/PhysRevLett.113.121102.

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    Ground Based Results Publications

      Bergstrom L, Bringmann T, Cholis I, Hooper D, Weniger C.  New limits on dark matter annihilation from Alpha Magnetic Spectrometer cosmic ray positron data. Physical Review Letters. 2013 October 25; 111(17): 171101. DOI: 10.1103/PhysRevLett.111.171101. PMID: 24206472.

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    ISS Patents

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    Related Publications

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    Related Websites
    Alpha Magnetic Spectrometer

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    AMS-02 integration activities in Geneva, Switzerland. Image courtesy of the Massachusetts Institute of Technology, Cambridge, MA.

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    Computer generated image of the completed International Space Station with external workstations. Image courtesy of NASA.

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    AMS-02 in the payload by of STS-134/ULF6, Endeavor on March 28, 2011. Image courtesy of Michele Famiglietti.

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    image AMS-02 is an international collaboration of 600 physicists from 56 institutes in16 countries led by Nobel Laureate Dr Samuel Ting of MIT.
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    NASA Image: S134E007532 - The starboard truss of the International Space Station is featured in this image photographed by an STS-134 crew member while space shuttle Endeavour remains docked with the station. The newly-installed Alpha Magnetic Spectrometer-2 (AMS) is visible at center left.

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    image NASA Image: S134E009289 - Alpha Magnetic Spectrometer - 2 (AMS-2) installed on the S3 truss segment next to the EXPRESS (Expedite the Processing of Experiments to Space Station) Logistics Carrier 2 (ELC2). Photo taken during STS-134 / Expedition 27 joint operations.
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    NASA Image: ISS035E022422 -

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