View source for Alpha Magnetic Spectrometer

{{short description|Particle detector on the International Space Station}}
{{Use mdy dates|date=September 2022}}
{{Infobox space station module
 | spelling               = us
 | module                 = Alpha Magnetic Spectrometer
 | module_image           = File:ISS-50_EVA-1_(b)_Alpha_Magnetic_Spectrometer.jpg
 | module_image_caption   = AMS-02 on the truss, as viewed during an [[Expedition 50]] spacewalk
 | station                = [[International Space Station]]
 | launch                 = {{start date text|16 May 2011 13:56:28}} [[UTC]]<ref name="launchslip2">{{cite web | url=http://www.space.com/11524-nasa-space-shuttle-launch-delay-endeavour.html | title=NASA Delays Last Launch of Shuttle Endeavour Due to Malfunction | work=Space.com | access-date=April 29, 2011 | author=Moskowitz, Clara| date=April 29, 2011 }}</ref><ref name=UT>[http://www.universetoday.com/tag/alpha-magnetic-spectrometer/ Final Shuttle Flight Will Be Delayed at Least Until November for AMS Switchout – April 26th, 2010]</ref><ref name="landing">{{Cite web|url=http://www.nasa.gov/mission_pages/shuttle/launch/index.html|title=Space Shuttle Launch and Landing|access-date=May 16, 2011|publisher=NASA| archive-url= https://web.archive.org/web/20110524172005/http://www.nasa.gov/mission_pages/shuttle/launch/index.html| archive-date= May 24, 2011 | url-status= live}}</ref>
 | launch_vehicle         = {{OV|105}}
 | berthed                = {{Start date and age|2011|05|19}}
 | mass                   = {{convert|6717|kg|abbr=on}}
}}
[[Image:AMS-02 Logo.png|thumb|AMS-02 logo]]
[[File:Alpha Magnetic Spectrometer - 02.jpg|thumb|Computer rendering of AMS-02]]

The '''Alpha Magnetic Spectrometer''' ('''AMS-02''') is a [[particle physics]] experiment module that is mounted on the [[International Space Station]] (ISS).<ref name="Rainey2013">Kristine Rainey (April 2, 2013). [https://www.nasa.gov/mission_pages/station/research/news/ams_how_it_works.html Alpha Magnetic Spectrometer (AMS): How It Works], NASA. Retrieved June 2, 2019.</ref> The experiment is a recognized [[CERN]] experiment (RE1).<ref>{{cite web |url=http://committees.web.cern.ch/rec/welcome.html |title=Recognized Experiments at CERN |website=The CERN Scientific Committees |publisher=CERN |access-date=January 20, 2020 |archive-date=June 13, 2019 |archive-url=https://web.archive.org/web/20190613150251/http://committees.web.cern.ch/rec/welcome.html |url-status=dead }}</ref><ref>{{cite web |url=https://greybook.cern.ch/greybook/experiment/detail?id=RE1 |title=RE1/AMS : Alpha Magnetic Spectrometer (AMS) for Extraterrestrial Study of Antimatter, Matter and Missing Matter on the International Space Station |publisher=CERN |access-date=January 20, 2020}}</ref> The module is a detector that measures [[antimatter]] in [[cosmic ray]]s; this information is needed to understand the formation of the [[universe]] and search for evidence of [[dark matter]].

The [[principal investigator]] is [[Nobel laureate]] particle physicist [[Samuel C. C. Ting|Samuel Ting]]. The launch of {{OV|105}} flight [[STS-134]] carrying AMS-02 took place on May 16, 2011, and the [[spectrometer]] was installed on May 19, 2011.<ref name=ESTEC2 /><ref>{{cite web |date=April 18, 2010 |title=AMS–NASA meeting results |url=http://www.ams02.org/2010/04/ams-nasa-meeting-results/ |url-status=dead |archive-url=https://web.archive.org/web/20100426071859/http://www.ams02.org/2010/04/ams-nasa-meeting-results/ |archive-date=April 26, 2010 |access-date=April 19, 2010 |publisher=AMS collaboration}}</ref> By April 15, 2015, AMS-02 had recorded over 60 billion cosmic ray events<ref name=AMS02>{{cite web|title="AMS Days at CERN" and Latest Results|url=http://www.ams02.org/2015/04/ams-days-at-cern-and-latest-results-from-the-ams-experiment-on-the-international-space-station/|website=AMS02.org|access-date=December 29, 2015|archive-url=https://web.archive.org/web/20190601221300/http://www.ams02.org/2015/04/ams-days-at-cern-and-latest-results-from-the-ams-experiment-on-the-international-space-station/|archive-date=June 1, 2019|url-status=dead}}</ref> and 90 billion after five years of operation since its installation in May 2011.<ref name = AMS02-2016>{{cite web|url=http://uhnatsci.org/files/news/AMSPressRelease.pdf|access-date=December 12, 2016|date=December 2016|publisher=AMS collaboration|title=The First Five years of AMS on the International Space Station|archive-date=July 12, 2022|archive-url=https://web.archive.org/web/20220712125952/https://uhnatsci.org/files/news/AMSPressRelease.pdf|url-status=dead}}</ref>

In March 2013, Professor Ting reported initial results, saying that AMS had observed over 400,000 [[positron]]s, with the positron to electron fraction increasing from 10 GeV to 250 GeV. (Later results have shown a decrease in positron fraction at energies over about 275 GeV). There was "no significant variation over time, or any preferred incoming direction. These results are consistent with the positrons originating from the annihilation of dark matter particles in space, but not yet sufficiently conclusive to rule out other explanations." The results have been published in ''[[Physical Review Letters]]''.<ref name="physrevltrs413">{{Cite journal | last1 = Aguilar | first1 = M. | last2 = Alberti | first2 = G. | last3 = Alpat | first3 = B. | last4 = Alvino | first4 = A. | last5 = Ambrosi | first5 = G. | last6 = Andeen | first6 = K. | last7 = Anderhub | first7 = H. | last8 = Arruda | first8 = L. | last9 = Azzarello | first9 = P. | last10 = Bachlechner | first10 = A. | last11 = Barao | first11 = F. | last12 = Baret | first12 = B. | last13 = Barrau | first13 = A. | last14 = Barrin | first14 = L. | last15 = Bartoloni | first15 = A. | last16 = Basara | first16 = L. | last17 = Basili | first17 = A. | last18 = Batalha | first18 = L. | last19 = Bates | first19 = J. | last20 = Battiston | first20 = R. | last21 = Bazo | first21 = J. | last22 = Becker | first22 = R. | last23 = Becker | first23 = U. | last24 = Behlmann | first24 = M. | last25 = Beischer | first25 = B. | last26 = Berdugo | first26 = J. | last27 = Berges | first27 = P. | last28 = Bertucci | first28 = B. | last29 = Bigongiari | first29 = G. | last30 = Biland | first30 = A. | title = 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 | doi = 10.1103/PhysRevLett.110.141102 | journal = Physical Review Letters | volume = 110 | issue = 14 | pages = 141102 | date = 2013 |bibcode = 2013PhRvL.110n1102A | display-authors = 29 | pmid=25166975| url = https://boa.unimib.it/bitstream/10281/44680/1/2013_PhysRevLett.110.141102_positron_fraction.pdf | doi-access = free }}</ref> Additional data are still being collected.<ref name="physrevltrs413" /><ref name="AMS-20130403">{{cite web |author=Staff |title=First Result from the Alpha Magnetic Spectrometer Experiment |url=http://www.ams02.org/2013/04/first-results-from-the-alpha-magnetic-spectrometer-ams-experiment/ |date=April 3, 2013 |work=AMS Collaboration |access-date=April 3, 2013 |archive-url=https://web.archive.org/web/20130408185229/http://www.ams02.org/2013/04/first-results-from-the-alpha-magnetic-spectrometer-ams-experiment/ |archive-date=April 8, 2013 |url-status=dead }}</ref><ref name="AP-20130403">{{cite news |last1=Heilprin |first1=John |last2=Borenstein |first2=Seth |title=Scientists find hint of dark matter from cosmos |url=http://apnews.excite.com/article/20130403/DA5E6JAG3.html |date=April 3, 2013 |work=[[AP News]] |access-date=April 3, 2013 |archive-url=https://web.archive.org/web/20130510152050/http://apnews.excite.com/article/20130403/DA5E6JAG3.html |archive-date=May 10, 2013 |url-status=dead  }}</ref><ref name="BBC-20130403">{{cite news |last=Amos |first=Jonathan |title=Alpha Magnetic Spectrometer zeroes in on dark matter |url=https://www.bbc.co.uk/news/science-environment-22016504 |date=April 3, 2013 |work=[[BBC]] |access-date=April 3, 2013 }}</ref><ref name="NASA-20130403">{{cite web |last1=Perrotto |first1=Trent J. |last2=Byerly |first2=Josh |title=NASA TV Briefing Discusses Alpha Magnetic Spectrometer Results |url=http://www.nasa.gov/home/hqnews/2013/apr/HQ_M13-054_AMS_Findings_Briefing.html |date=April 2, 2013 |work=[[NASA]] |access-date=April 3, 2013 }}</ref><ref name="NYT-20130403">{{cite news |last=Overbye |first=Dennis |title=New Clues to the Mystery of Dark Matter |url=https://www.nytimes.com/2013/04/04/science/space/new-clues-to-the-mystery-of-dark-matter.html |date=April 3, 2013 |work=[[The New York Times]] |access-date=April 3, 2013 }}</ref><ref>{{Cite web | url=http://home.web.cern.ch/about/updates/2013/04/ams-experiment-measures-antimatter-excess-space | title=AMS experiment measures antimatter excess in space| date=July 18, 2024}}</ref>

==History==
The alpha magnetic spectrometer was proposed in 1995 by the '''Antimatter Study Group''',<ref name="AMS1994" /><ref name="Rainey2013" /> led by [[Massachusetts Institute of Technology|MIT]] particle physicist Samuel Ting, not long after the cancellation of the [[Superconducting Super Collider]]. The original name for the instrument was '''Antimatter Spectrometer''',<ref name="Rainey2013" /><ref name="AMS1994">{{Cite journal | doi=10.1016/0168-9002(94)91184-3| title=An antimatter spectrometer in space| journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment| volume=350| issue=1–2| pages=351–367| year=1994| last1=Ahlen| first1=S.| last2=Balebanov| first2=V.M.| last3=Battiston| first3=R.| last4=Becker| first4=U.| last5=Burger| first5=J.| last6=Capell| first6=M.| last7=Chen| first7=H.F.| last8=Chen| first8=H.S.| last9=Chen| first9=M.| last10=Chernoplekov| first10=N.| last11=Clare| first11=R.| last12=Dai| first12=T.S.| last13=De Rujula| first13=A.| last14=Fisher| first14=P.| last15=Galaktionov| first15=Yu.| last16=Gougas| first16=A.| last17=Wen-Qi| first17=Gu| last18=He| first18=M.| last19=Koutsenko| first19=V.| last20=Lebedev| first20=A.| last21=Li| first21=T.P.| last22=Lu| first22=Y.S.| last23=Luckey| first23=D.| last24=Ma| first24=Y.| last25=McNeil| first25=R.| last26=Orava| first26=R.| last27=Prevsner| first27=A.| last28=Plyaskine| first28=V.| last29=Rubinstein| first29=H.| last30=Sagdeev| first30=R.| display-authors=1|collaboration=Antimatter Study Group| bibcode=1994NIMPA.350..351A}}</ref><ref name =Battiston2008>{{cite journal | last1 = Battiston | first1 = Roberto | year = 2008| title = The antimatter spectrometer (AMS-02) A particle physics detector in space | url = https://cds.cern.ch/record/965843| journal = Nuclear Instruments and Methods in Physics Research Section A | volume = 588| issue = 1–2| pages = 227–234| doi = 10.1016/j.nima.2008.01.044 | bibcode = 2008NIMPA.588..227B }}</ref> with the stated objective to search for primordial antimatter, with a target resolution of antimatter/matter ≈10<sup>−9</sup>.<ref name="AMS1994"/><ref name =Battiston2008/> The proposal was accepted and Ting became the [[principal investigator]].<ref name="nyt">{{cite news|first=Dennis |last=Overbye
|url=https://www.nytimes.com/2007/04/03/science/space/03stat.html?ex=1333252800&en=4c210875b60f26e6&ei=5088&partner=rssnyt&emc=rss|title= Long-Awaited Cosmic-Ray Detector May Be Shelved|work= [[The New York Times]]|date=April 3, 2007}}</ref>

===AMS-01===
{{multiple image
| image1 = STS-91 PLB.jpg
| width1 = {{#expr: (200 * (1035 / 1451)) round 0}}
| alt1 = 
| caption1 = AMS-01 flew in space in June 1998 aboard the [[Space Shuttle Discovery|Space Shuttle ''Discovery'']] on [[STS-91]]. It is visible near the rear of the payload bay.
| image2 = STS-91 AMS-01 Detail.jpg
| width2 = {{#expr: (200 * (234 / 171)) round 0}}
| alt2 = 
| caption2 = A detail view of the AMS-01 module (center) mounted in the [[Space Shuttle Discovery|shuttle]] payload bay for the [[STS-91]] mission.
| footer = 
}}
An AMS prototype designated '''AMS-01''', a simplified version of the detector, was built by the international consortium under Ting's direction and flown into space aboard the {{OV|103}} on [[STS-91]] in June 1998. By not detecting any [[antihelium#Antihelium|antihelium]], the AMS-01 established an upper limit of 1.1×10<sup>−6</sup> for the antihelium-to-helium [[flux]] ratio<ref>{{cite journal |journal=Physics Reports |volume=366 |issue=6 |pages=331–405 |date=August 2002 |author=AMS Collaboration |last2=Aguilar |first2=M. |last3=Alcaraz |first3=J. |last4=Allaby |first4=J. |last5=Alpat |first5=B. |last6=Ambrosi |first6=G. |last7=Anderhub |first7=H. |last8=Ao |first8=L. |last9=Arefiev |first9=A. |display-authors=8|title=The Alpha Magnetic Spectrometer (AMS) on the International Space Station: Part I – results from the test flight on the space shuttle |bibcode=2002PhR...366..331A |doi=10.1016/S0370-1573(02)00013-3|s2cid=122726107 |hdl=2078.1/72661 |hdl-access=free }}</ref> and proved that the detector concept worked in space. This shuttle mission was the last shuttle flight to the [[Mir|''Mir'' space station]].
{{Clear}}

=== AMS-02 ===
[[File:AMS01Geneva.jpg|thumb|right|AMS-02 during integration and testing at [[CERN]] near Geneva, Switzerland.]]
After the flight of the prototype, the group, now labelled the '''AMS Collaboration''', began the development of a full research system designated '''AMS-02'''. This development effort involved the work of 500 scientists from 56 institutions and 16 countries organized under [[United States Department of Energy]] (DOE) sponsorship.

The instrument which eventually resulted from a long evolutionary process has been called "the most sophisticated particle detector ever sent into space", rivaling very large detectors used at major [[particle accelerator]]s, and has cost four times as much as any of its ground-based counterparts. Its goals have also evolved and been refined over time. As built it is a more comprehensive detector which has a better chance of discovering evidence of [[dark matter]] along with other goals.<ref>Controversy Follows Pricey Space Station Experiment to Launch Pad, SCIENCE, Vol. 332, April 22, 2011.</ref>

The power requirements for AMS-02 were thought to be too great for a practical independent spacecraft, so AMS-02 was designed to be installed as an external module on the International Space Station and use power from the ISS. The post-{{OV|102}} plan was to deliver AMS-02 to the ISS by space shuttle in 2005 on [[assembly of the International Space Station|station assembly]] mission '''UF4.1''', but technical difficulties and shuttle scheduling issues added more delays.<ref name="overview">{{cite web
| first=Benjamin |last=Monreal
| url=http://cyclo.mit.edu/ams/frames.mission.html
| title=AMS experiment mission overview
| work =AMS Experiment Guided Tour 
| publisher =AMS-02 Collaboration
| access-date=September 3, 2009}}</ref>

AMS-02 completed final integration and operational testing at [[CERN]] in [[Geneva, Switzerland]] which included exposure to energetic [[proton]] beams generated by the CERN [[Super Proton Synchrotron|SPS particle accelerator]].<ref>{{cite web
 | title =LEAVING CERN, ON THE WAY TO ESTEC
 | work =AMS in The News
 | publisher =AMS-02
 | date =February 16, 2010
| url =http://www.ams02.org/2010/02/leaving-cern/
 | access-date =April 9, 2013
| archive-url =https://web.archive.org/web/20111001001441/http://www.ams02.org/2010/02/leaving-cern/
 | archive-date =October 1, 2011
| url-status =dead
 }}</ref><ref>{{cite web
 | title =Dark Matter Detective Arrives At ESTEC
 | work =Space Daily
 | publisher =spacedaily.com
 | date =February 17, 2010
| url =http://ams.nasa.gov/Documents/AMS%20in%20The%20News/Space%20Daily%20-%20AMS%20Arrives%20at%20ESTEC.pdf
}}</ref> AMS-02 was then shipped by [http://www.route-to-space.eu/index.php/en/projects/alpha-magnetic-spectrometer specialist hauler] <ref>{{Webarchive|url=https://web.archive.org/web/20220117022853/http://www.route-to-space.eu/index.php/en/projects/alpha-magnetic-spectrometer |date=January 17, 2022 }}</ref> to [[European Space Agency|ESA's]] [[European Space Research and Technology Centre]] (ESTEC) facility in the [[Netherlands]], arriving February 16, 2010. Here it underwent thermal vacuum, [[electromagnetic compatibility]], and [[electromagnetic interference]] testing. AMS-02 was scheduled for delivery to the [[Kennedy Space Center]] in [[Florida]], United States, in late May 2010.<ref name=ESTEC2>{{cite web | title=A final test for AMS at ESTEC | access-date=February 20, 2010| publisher=CERN | date=February 22, 2010 | work=The Bulletin | url=http://cdsweb.cern.ch/journal/CERNBulletin/2010/08/News%20Articles/1241789?ln=en}}</ref> This was, however, postponed to August 26, as AMS-02 underwent final alignment beam testing at CERN.<ref name="amsliftedatgva">{{Cite AV media |url=https://www.youtube.com/watch?v=rJcYYbtq96U |title=C5-M Aircraft with the AMS Detector aboard starting from GVA airport |language=en |access-date=2024-05-08 |via=www.youtube.com}}</ref><ref name=ESTEC>{{cite web | title=Waiting for the Alpha Magnetic Spectrometer | url=http://www.esa.int/esaHS/SEMGO8AK73G_index_0.html
| date=December 17, 2009 | publisher=[[European Space Agency|ESA]] News | access-date=January 9, 2010| archive-url= https://web.archive.org/web/20100126083035/http://www.esa.int/esaHS/SEMGO8AK73G_index_0.html| archive-date= January 26, 2010 | url-status= live}}</ref>

{{multiple image
| align             = left
| image1            = Amsbeamtesting.JPG
| width1            = 200
| alt1              = 
| caption1          = AMS-02 during final alignment testing at [[CERN]] just days before being airlifted to [[Kennedy Space Center|Cape Canaveral]], Florida.
| image2            = Beamfeedingams.JPG
| width2            = 200
| alt2              = 
| caption2          = Beamline from [[Super Proton Synchrotron|SPS]] feeding 20 GeV [[positron]]s to AMS for alignment testing at the time of the picture.
| footer            = 
}}

A cryogenic, [[superconducting magnet]] system was initially installed on the AMS-02. When the [[Obama administration]] extended International Space Station operations beyond 2015, the decision was made by AMS management to exchange the AMS-02 superconducting magnet for the non-superconducting magnet previously flown on AMS-01. Although the non-superconducting magnet has a weaker [[field strength]], its on-orbit operational time at ISS is expected to be 10 to 18 years versus only three years for the superconducting version.<ref name="AWST">{{cite web
 |title=AMS To Get Longer Lease On Life 
 |url=http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/asd/2010/04/22/07.xml 
 |date=April 23, 2010 |work=Aviation Week and Space Technology 
 |access-date=April 23, 2010 |archive-url=https://web.archive.org/web/20120326162133/http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news%2Fasd%2F2010%2F04%2F22%2F07.xml 
 |archive-date=March 26, 2012 |url-status=dead 
}}</ref> In December 2018, it was announced that funding for the ISS had been extended to 2030.<ref>{{cite tweet|number=1075840067569139712|user=SenBillNelson|title=The Senate just passed my bill to...|date=December 20, 2018}}</ref>

In 1999, after the successful flight of AMS-01, the total cost of the AMS program was estimated to be $33 million, with AMS-02 planned for flight to the ISS in 2003.<ref>{{cite web | publisher=SPACE.com | first=Greg |last=Clark | title=NASA Puts Big Bang to the Test | date=October 15, 1999 | url=http://www.space.com/news/spacestation/iss_antimatter991015.html | access-date=September 20, 2009 | archive-url=https://web.archive.org/web/20030203062748/http://www.space.com/news/spacestation/iss_antimatter991015.html | archive-date=February 3, 2003}}</ref> After the [[Space Shuttle Columbia disaster|Space Shuttle ''Columbia'' disaster]] in 2003, and after a number of technical difficulties with the construction of AMS-02, the cost of the program ballooned to an estimated $2 billion.<ref>{{cite web |author=Musser |first=George |date=May 2011 |title=Cosmic-Ray Detector on Space Shuttle Set to Scan Cosmos for Dark Matter |url=http://www.scientificamerican.com/article/the-space-stations-crown-jewel/ |access-date=January 24, 2014 |publisher=[[Scientific American]]}}</ref><ref name="Hsu">{{cite web
| url=http://www.space.com/businesstechnology/090902-tw-antimatter-hunter.html
| title=Space Station Experiment to Hunt Antimatter Galaxies
| publisher=Space.com
| date=September 2, 2009
| first=Jeremy |last=Hsu
| access-date=September 2, 2009| archive-url= https://web.archive.org/web/20091006020704/http://www.space.com/businesstechnology/090902-tw-antimatter-hunter.html| archive-date= October 6, 2009 | url-status= live}}</ref>

===Installation on the International Space Station===
{{multiple image
| align = right
| image1 = AMS02onISS.jpg
| width1 = {{#expr: (140 * (6000 / 3375)) round 0}}
| alt1 = 
| caption1 = A computer generated image showing AMS-02 mounted to the [[ISS]] S3 Upper Inboard Payload Attach Site.
| image2 = ISS Unpressurized Platforms.png
| width2 = {{#expr: (140 * (1414 / 540)) round 0}}
| alt2 = 
| caption2 = Location of the AMS on the [[International Space Station]] (upper left).
| footer = 
}}
[[Image:STS-134 the starboard truss of the ISS with the newly-installed AMS-02.jpg|thumb|right|AMS-02 installed on the [[ISS]].]]
For several years it was uncertain if AMS-02 would ever be launched because it was not manifested to fly on any of the remaining [[Space Shuttle]] flights.<ref name="wp-2007">{{cite news|url=https://www.washingtonpost.com/wp-dyn/content/article/2007/12/01/AR2007120100760.html|title=The Device NASA Is Leaving Behind|first=Marc |last=Kaufman|newspaper=Washington Post|date=December 2, 2007|access-date=December 2, 2007}}</ref> After the 2003 [[Space Shuttle Columbia disaster|''Columbia'' disaster]], NASA decided to reduce shuttle flights and retire the remaining shuttles by 2010. A number of flights were removed from the remaining manifest, including the flight for AMS-02.<ref name="nyt"/> In 2006, NASA studied alternative ways of delivering AMS-02 to the space station, but they all proved to be too expensive.<ref name="wp-2007" />

In May 2008, a bill<ref>{{Cite web |url=http://thomas.loc.gov/cgi-bin/bdquery/z?d110:h.r.06063: |title=bill |access-date=October 6, 2008 |archive-date=November 25, 2008 |archive-url=https://web.archive.org/web/20081125180609/http://thomas.loc.gov/cgi-bin/bdquery/z?d110:h.r.06063: |url-status=dead }}</ref> was proposed to launch AMS-02 to the ISS on an additional shuttle flight in 2010 or 2011.<ref name="House Bill Would Authorize Additional Shuttle Flights">{{cite web|url=http://www.space.com/missionlaunches/080519-house-bill-shuttle-extension.html|title=House Bill Would Authorize Additional Shuttle Flights|date=May 19, 2008|first=Becky |last=Iannotta|publisher=Space.com|access-date=May 19, 2008| archive-url= https://web.archive.org/web/20080520062702/http://www.space.com/missionlaunches/080519-house-bill-shuttle-extension.html| archive-date= May 20, 2008 | url-status= live}}</ref> The bill was passed by the full U.S. [[United States House of Representatives|House of Representatives]] on June 11, 2008.<ref>{{cite video|people= David Kestenbaum|date=June 10, 2008|title= NASA balks at Taking Physics Gear Into Space|url= https://www.npr.org/templates/story/story.php?storyId=91360621|medium= Radio production|publisher= National Public Radio|location= [[Washington, D.C.]]|access-date=June 10, 2008}}</ref> The bill then went before the [[United States Senate Committee on Commerce, Science, and Transportation|Senate Commerce, Science and Transportation Committee]] where it also passed. It was then amended and passed by the full [[United States Senate|Senate]] on September 25, 2008, and was passed again by the House on September 27, 2008.<ref name="Congress Passes Final Version HR6063">{{cite press release|url=http://science.house.gov/press/PRArticle.aspx?NewsID=2309|date=September 27, 2008|publisher=House Science and Technology Committee|title=House Sends NASA Bill to President's Desk, Reaffirms Commitment to Balanced and Robust Space and Aeronautics Program|url-status=dead|archive-url=https://web.archive.org/web/20100527142718/http://science.house.gov/press/PRArticle.aspx?NewsID=2309|archive-date=May 27, 2010}}</ref> It was signed into law by President [[George W. Bush]] on October 15, 2008.<ref name="Bush Signs NASA Authorization Act">{{cite web |last=Matthews |first=Mark |date=October 15, 2008 |title=Bush Signs NASA Authorization Act |url=http://blogs.orlandosentinel.com/news_space_thewritestuff/2008/10/bush-signs-nasa.html |url-status=dead |archive-url=https://web.archive.org/web/20081019025713/http://blogs.orlandosentinel.com/news_space_thewritestuff/2008/10/bush-signs-nasa.html |archive-date=October 19, 2008 |publisher=Orlando Sentinel |language=en-us |publication-place=Orlando, Florida}}</ref><ref name="Library of Congress - H.R.6063 - Major Actions">{{cite web|url=http://thomas.loc.gov/cgi-bin/bdquery/z?d110:HR06063:@@@R|title=Major Actions: H.R. 6063|publisher=THOMAS (Library of Congress)|date=October 15, 2008|access-date=October 16, 2008|archive-date=November 20, 2008|archive-url=https://web.archive.org/web/20081120194303/http://thomas.loc.gov/cgi-bin/bdquery/z?d110:HR06063:@@@R|url-status=dead}}</ref> The bill authorized NASA to add another space shuttle flight to the schedule before the space shuttle program was discontinued. In January 2009, NASA restored AMS-02 to the shuttle manifest. On August 26, 2010, AMS-02 was delivered from [[CERN]] to the [[Kennedy Space Center]] by a [[Lockheed C-5 Galaxy]] jet.<ref>{{Cite AV media |url=https://www.youtube.com/watch?v=rxERIDL8Cw0 |title=CERN News – August 28, 2010: AMS From CERN to Space! |language=en |access-date=2024-05-08 |via=www.youtube.com}}</ref>

It was delivered to the [[International Space Station]] on May 19, 2011, as part of station assembly flight '''ULF6''' on shuttle flight [[STS-134]], commanded by [[Mark Kelly (astronaut)|Mark Kelly]].<ref name="manifest">{{cite web
| url=http://www.nasa.gov/mission_pages/station/structure/iss_manifest.html
| title=Consolidated Launch Manifest
| date=August 25, 2009
| publisher=NASA
| access-date=September 3, 2009| archive-url= https://web.archive.org/web/20090831041621/http://www.nasa.gov/mission_pages/station/structure/iss_manifest.html| archive-date= August 31, 2009 | url-status= live}}</ref> It was removed from the shuttle cargo bay using the shuttle's robotic arm and handed off to the station's robotic arm for installation. AMS-02 is mounted on top of the [[Integrated Truss Structure]], on USS-02, the [[zenith]] side of the [[Integrated Truss Structure#P3.2FP4.2C S3.2FS4 truss assemblies|S3-element]] of the truss.<ref name="NASA-AMS-02">{{cite web
 |url=http://www.nasa.gov/mission_pages/station/science/experiments/AMS-02.html 
 |title=Alpha Magnetic Spectrometer – 02 (AMS-02) 
 |publisher=NASA 
 |date=August 21, 2009 |access-date=September 3, 2009 |url-status=dead 
 |archive-url=https://web.archive.org/web/20090816041406/http://www.nasa.gov/mission_pages/station/science/experiments/AMS-02.html 
 |archive-date=August 16, 2009 }}</ref>

===Operations, condition and repairs===
[[File:ISS-61 EVA-6 (b) Luca Parmitano carries the new thermal pump system.jpg|thumb|left|[[European Space Agency|ESA]] astronaut [[Luca Parmitano]], attached to the [[Mobile Servicing System|Canadarm2]] robotic arm, carries the new thermal pump system for AMS]]
By April 2017, only one of the 4 redundant coolant pumps for the silicon trackers was fully working, and repairs were being planned, despite AMS-02 not being designed to be serviced in space.<ref>[https://www.science.org/content/article/giant-space-magnet-may-have-trapped-antihelium-raising-idea-lingering-pools-antimatter ''Giant space magnet may have trapped antihelium, raising idea of lingering pools of antimatter in the cosmos''].</ref><ref name=AMS-repair/> By 2019, the last pump was being operated intermittently.<ref name="AMS-repair">{{Cite web |title=Repair equipment for particle physics experiment aboard next station cargo launch – Spaceflight Now |url=https://spaceflightnow.com/2019/11/01/repair-equipment-for-particle-physics-experiment-aboard-next-station-cargo-launch/ |access-date=2024-05-08 |language=en-US}}</ref> In November 2019, after four years of planning,<ref name=AMS-repair/> special tools and equipment were sent to the ISS for in-situ repairs requiring four [[Extravehicular activity|EVAs]].<ref>{{Cite web|url=https://spaceflightnow.com/2019/11/04/space-station-receives-spacewalking-gear-new-baking-oven/|title = Space station receives spacewalking gear, new baking oven – Spaceflight Now}}</ref> Liquid carbon dioxide coolant was also replenished.<ref name=AMS-repair/>

The repairs were conducted by the ISS crew of [[Expedition 61]]. The spacewalkers were the expedition commander and [[European Space Agency|ESA]] astronaut [[Luca Parmitano]], and [[NASA]] astronaut [[Andrew R. Morgan|Andrew Morgan]]. Both of them were assisted by NASA astronauts [[Christina Koch]] and [[Jessica Meir]] who operated the [[Mobile Servicing System|Canadarm2]] robotic arm from inside the Station. The spacewalks were described as the "most challenging since [the last] [[STS-125|Hubble repairs]]".<ref>{{Cite web|url=http://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/Luca_to_lead_most_challenging_spacewalks_since_Hubble_repairs|title=Luca to lead most challenging spacewalks since Hubble repairs|website=www.esa.int|language=en|access-date=January 26, 2020}}</ref>

The entire spacewalk campaign was a central feature of the [[List of Disney+ original programming|Disney+ docuseries Among The Stars]].

==== First spacewalk ====
The first spacewalk was conducted on November 15, 2019. The spacewalk began with the removal of the debris shield covering AMS, which was jettisoned to burn up in the atmosphere. The next task was to install three handrails in the vicinity of AMS to prepare for the next spacewalks and remove zip ties on the AMS' vertical support strut. This was followed by the "get ahead" tasks: Parmitano removed the screws from a carbon-fibre cover under the insulation and passed the cover to Morgan to jettison. The spacewalkers also removed the vertical support beam cover. The duration of the spacewalk was 6 hours and 39 minutes.<ref>{{Cite web|url=http://www.esa.int/ESA_Multimedia/Images/2019/11/A_very_good_start|title=A very good start|website=www.esa.int|language=en|access-date=January 26, 2020}}</ref><ref>{{Cite web|url=https://blogs.nasa.gov/spacestation/2019/11/15/spacewalkers-complete-first-excursion-to-repair-cosmic-particle-detector/|title=Spacewalkers Complete First Excursion to Repair Cosmic Particle Detector – Space Station|website=blogs.nasa.gov|language=en-US|access-date=January 26, 2020|archive-date=November 15, 2019|archive-url=https://web.archive.org/web/20191115234246/https://blogs.nasa.gov/spacestation/2019/11/15/spacewalkers-complete-first-excursion-to-repair-cosmic-particle-detector/|url-status=dead}}</ref>

==== Second spacewalk ====
The second spacewalk was conducted on November 22, 2019. Parmitano and Morgan cut a total of eight stainless steel tubes, including one that vented the remaining carbon dioxide from the old cooling pump. The crew members also prepared a power cable and installed a mechanical attachment device in advance of installing the new cooling system. The duration of the spacewalk was 6 hours and 33 minutes.<ref>{{Cite web|url=https://blogs.nasa.gov/spacestation/2019/11/22/astronauts-complete-intricate-tasks-during-second-cosmic-repair-spacewalk/|title=Astronauts Complete Intricate Tasks During Second Cosmic Repair Spacewalk – Space Station|website=blogs.nasa.gov|language=en-US|access-date=January 26, 2020|archive-date=June 5, 2020|archive-url=https://web.archive.org/web/20200605192446/https://blogs.nasa.gov/spacestation/2019/11/22/astronauts-complete-intricate-tasks-during-second-cosmic-repair-spacewalk/|url-status=dead}}</ref>

==== Third spacewalk ====
The third spacewalk was conducted on December 2, 2019. The crew completed the primary task of installing the upgraded cooling system, called the upgraded tracker thermal pump system (UTTPS), completed the power and data cable connections for the system, and connected all eight cooling lines from the AMS to the new system. The intricate connection work required making a clean cut for each existing stainless steel tube connected to the AMS, then connecting it to the new system through [[swaging]].<ref name=":0">{{Cite web|url=https://blogs.nasa.gov/spacestation/2019/12/02/astronauts-wrap-up-third-spacewalk-for-cosmic-particle-detector-repairs/|title=Astronauts Wrap Up Third Spacewalk for Cosmic Particle Detector Repairs – Space Station|website=blogs.nasa.gov|date=December 2, 2019 |language=en-US|access-date=January 26, 2020}}</ref>

The astronauts also completed an additional task to install an insulating blanket on the [[nadir]] side of the AMS to replace the heat shield and blanket they removed during the first spacewalk to begin the repair work. The flight control team on Earth initiated power-up of the system and confirmed its reception of power and data.<ref name=":0" />

The duration of the spacewalk was 6 hours and 2 minutes.<ref name=":0" />

==== Fourth spacewalk ====
The fourth spacewalk was conducted on January 25, 2020. The astronauts conducted leak checks for the cooling system on the AMS and opened a valve to pressurize the system. Parmitano found a leak in one of the AMS's cooling lines. The leak was fixed during the spacewalk. Preliminary testing showed the AMS was responding as expected.<ref name=":1">{{Cite web|url=https://blogs.nasa.gov/spacestation/2020/01/25/astronauts-wrap-up-spacewalk-repair-job-on-cosmic-ray-detector/|title=Astronauts Wrap Up Spacewalk Repair Job on Cosmic Ray Detector – Space Station|website=blogs.nasa.gov|date=January 25, 2020 |language=en-US|access-date=January 26, 2020}}</ref><ref>{{Cite web|url=https://www.euronews.com/2020/01/25/we-did-it-nasa-astronauts-complete-spacewalk-to-fix-cosmic-ray-detector|title=NASA astronauts complete space-walk to fix cosmic ray detector|last=Crowcroft|first=Orlando|date=January 25, 2020|website=euronews|language=en|access-date=January 26, 2020}}</ref>

Ground teams worked to fill the new AMS thermal control system with [[carbon dioxide]], allowed the system to stabilize, and powered on the pumps to verify and optimize their performance. The tracker, one of several detectors on the AMS, began collecting science data again before the end of the week after the spacewalk.<ref name=":1" />

The astronauts also completed an additional task to remove degraded lens filters on two high-definition video cameras.<ref name=":1" />

The duration of the spacewalk was 6 hours and 16 minutes.<ref name=":1" />

==Specifications==
*Mass: {{convert|7,500|kg|lbs}}
*Structural material: Stainless steel
*Power: 2,500&nbsp;W
*Internal data rate: 7&nbsp;Gbit/s
*Data rate to ground: 2&nbsp;Mbit/s (typical, average)<ref name="ams-facts-figures" />
*Primary mission duration: 10 to 18 years
* Design life: 3 years.<ref name=AMS-repair/>
*Magnetic field intensity: 0.15 [[tesla (unit)|tesla]] produced by a {{convert|1,200|kg|lb|abbr=on}} permanent [[neodymium magnet]]<ref name="ams-facts-figures">{{Cite web |title=AMS-02 » AMS in a Nutshell |url=http://www.ams02.org/what-is-ams/ams-facts-figures/ |url-status=dead |archive-url=https://web.archive.org/web/20110727125113/http://www.ams02.org/what-is-ams/ams-facts-figures/ |archive-date=July 27, 2011 |access-date=April 25, 2011}}</ref>
*Original superconducting magnet: 2 coils of [[niobium-titanium]] at 1.8&nbsp;K producing a central field of 0.87 [[tesla (unit)|tesla]]<ref>{{cite journal |last1=Blau |first1=B. |last2=Harrison |first2=S. M. |last3=Hofer |first3=H. |last4=Horvath |first4=I. L. |last5=Milward |first5=S. R. |last6=Ross |first6=J. S. H. |last7=Ting |first7=S. C. C. |last8=Ulbricht |first8=J. |last9=Viertel |first9=G. |date=2002 |title=The superconducting magnet system of AMS-02 – a particle physics detector to be operated on the International Space Station |journal=IEEE Transactions on Applied Superconductivity |volume=12 |issue=1 |pages=349–352 |bibcode=2002ITAS...12..349B |doi=10.1109/TASC.2002.1018417}}</ref> (not used in the actual device)
*AMS-02 flight magnet changed to non-superconducting AMS-01 version to extend experiment life and to solve reliability problems in the operation of the superconducting system
About 1,000 cosmic rays are recorded by the instrument per second, generating about one [[gigabyte|GB/s]] of data. This data is filtered and compressed to about 300&nbsp;kbit/s for download to the operation center POCC at CERN.

A mockup of the machine is present inside the operations center at CERN.

==Design==
The detector module consists of a series of detectors that are used to determine various characteristics of the radiation and particles as they pass through. Characteristics are determined only for particles that pass through from top to bottom. Particles that enter the detector at any other angles are rejected. From top to bottom the subsystems are identified as:<ref>{{cite web
 |url         = http://cyclo.mit.edu/~bmonreal/frames.det.html
 |title       = The AMS Experiment
 |first       = Benjamin
 |last        = Monreal
 |publisher   = MIT
 |access-date  = September 3, 2009
|url-status     = dead
 |archive-url  = https://web.archive.org/web/20100209032914/http://cyclo.mit.edu/~bmonreal/frames.det.html
 |archive-date = February 9, 2010
}}</ref>

*[[Transition radiation detector]] measures the velocities of the highest energy particles;
*Upper time of flight counter, along with the lower time of flight counter, measures the velocities of lower energy particles;
*Star tracker determines the orientation of the module in space;
*Silicon tracker (9 disks among 6 locations) measures the coordinates of charged particles in the magnetic field;
**Has 4 redundant coolant pumps
*Permanent magnet bends the path of charged particles so they can be identified;
*Anti-coincidence counter rejects stray particles that enter through the sides;
*[[Ring imaging Cherenkov detector]] measures velocity of fast particles with extreme accuracy;
*Electromagnetic calorimeter measures the total energy of the particles.

==Scientific goals==
The AMS-02 uses the unique environment of space to advance knowledge of the Universe and lead to the understanding of its origin by searching for antimatter, [[dark matter]] and measuring [[cosmic ray]]s.<ref name="NASA-AMS-02" />

===Antimatter===
{{See also|Antimatter}}
Experimental evidence indicates that [[Milky Way|our galaxy]] is made of [[matter]]; however, scientists believe there are about 100–200 billion galaxies in the observable Universe and some versions of the [[Big Bang]] theory of the origin of the Universe require 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 space. In 1999, ''AMS-01'' established a new upper limit of 10<sup>−6</sup> for the antihelium/helium flux ratio in the Universe. AMS-02 was designed to search with a sensitivity of 10<sup>−9</sup>,<ref name =Battiston2008 /> an improvement of three orders of magnitude over ''AMS-01'', sufficient to reach the edge of the expanding Universe and resolve the issue definitively.

===Dark matter===
{{See also|Dark matter}}
The visible matter in the Universe, such as 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]], [[antiproton]], or [[gamma ray]] flux could signal the presence of neutralinos or other dark matter candidates, but would need to be distinguished from poorly known [[confounding]] astrophysical signals.

===Strangelets===
{{See also|Strangelet}}
Six types of [[quark]]s ([[up quark|up]], [[down quark|down]], [[strange quark|strange]], [[charm quark|charm]], [[bottom quark|bottom]] and [[top quark|top]]) have been found experimentally; however, the majority of matter on Earth is made up of only up and down quarks. It is a fundamental question whether there exists stable matter made up of strange quarks in combination with up and down quarks. Particles of such matter are known as [[strangelet]]s. Strangelets might have extremely large mass and very small charge-to-mass ratios. It would be a totally new form of matter. AMS-02 may determine whether this extraordinary matter exists in our local environment.

===Space radiation environment===
[[Cosmic ray|Cosmic radiation]] during transit is a significant obstacle to [[human mission to Mars|sending humans to Mars]]. Accurate measurements of the cosmic ray environment are needed to plan appropriate countermeasures. Most cosmic ray studies are done by balloon-borne instruments with flight times that are measured in days; these studies have shown significant variations. AMS-02 operates on the [[International Space Station|ISS]], gathering a large 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 [[proton]]s to [[iron]]. In addition to understanding the radiation protection required for astronauts during [[human spaceflight|interplanetary flight]], this data will allow the interstellar propagation and origins of cosmic rays to be identified.

==Results==
{{update section|date=April 2024|with=any recent papers on AMS}}
By late 2016, it was reported that AMS-02 had observed over 90 billion cosmic rays.<ref name="AMS02-2016" />

In February 2013, Samuel Ting reported that in its first 18 months of operation AMS had recorded 25 billion particle events including nearly eight billion fast electrons and positrons.<ref name="BBC_2013-02-18" /> The AMS paper reported the positron-electron ratio in the mass range of 0.5 to 350 [[GeV]], providing evidence about the [[weakly interacting massive particle]] (WIMP) model of dark matter.

On March 30, 2013, the first results from the AMS experiment were announced by the [[CERN]] press office.<ref name="physrevltrs413" /><ref name="AMS-20130403" /><ref name="AP-20130403" /><ref name="BBC-20130403" /><ref name="NASA-20130403" /><ref name="NYT-20130403" /><ref name="First result from the AMS experiment">{{cite web
 |url=http://press.web.cern.ch/backgrounders/first-result-ams-experiment 
 |title=First result from the AMS experiment 
 |publisher=CERN press office 
 |date=March 30, 2013 |access-date=April 3, 2013 |url-status=dead 
 |archive-url=https://web.archive.org/web/20130407040617/http://press.web.cern.ch/backgrounders/first-result-ams-experiment 
 |archive-date=April 7, 2013 }}</ref> The first physics results were published in ''[[Physical Review Letters]]'' on April 3, 2013.<ref name="physrevltrs413" /> A total of 6.8 million [[positron]] and [[electron]] events were collected in the energy range from 0.5 to 350 GeV. The positron fraction (of the total electron plus positron events) steadily increased from energies of 10 to 250 GeV, but the slope decreased by an order of magnitude above 20 GeV, even though the fraction of positrons still increased. There was no fine structure in the positron fraction spectrum, and no [[anisotropies]] were observed. The accompanying ''Physics'' Viewpoint<ref>{{Cite magazine | last1 = Coutu | first1 = S. | title = Positrons Galore | doi = 10.1103/Physics.6.40 | magazine = Physics | volume = 6 | pages = 40 | date = 2013 |bibcode = 2013PhyOJ...6...40C | url = https://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.110.141102 | doi-access = free }}</ref> said that "The first results from the space-borne Alpha Magnetic Spectrometer confirm an unexplained excess of high-energy positrons in Earth-bound cosmic rays." These results are consistent with the positrons originating from the annihilation of dark matter particles in space, but not yet sufficiently conclusive to rule out other explanations. Ting said "Over the coming months, AMS will be able to tell us conclusively whether these positrons are a signal for dark matter, or whether they have some other origin."<ref>{{cite web| url=http://home.web.cern.ch/about/updates/2013/04/ams-experiment-measures-antimatter-excess-space| title= AMS experiment measures antimatter excess in space| date= July 18, 2024}}</ref>

On September 18, 2014, new results with almost twice as much data were presented in a talk at CERN and published in ''Physical Review Letters''.<ref>{{cite journal |author=Accardo |first=L. |author2=AMS Collaboration |date=September 18, 2014 |title=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 |url=http://ams.nasa.gov/Documents/AMS_Publications/PhysRevLett.113.121101.pdf |journal=Physical Review Letters |volume=113 |issue=12 |page=121101 |bibcode=2014PhRvL.113l1101A |doi=10.1103/PhysRevLett.113.121101 |pmid=25279616 |doi-access=free}}</ref><ref>{{cite web|title=New results from the Alpha Magnetic Spectrometer on the International Space Station|url=http://ams.nasa.gov/Documents/AMS_Publications/ams_new_results_-_18.09.2014.pdf|website=AMS-02 at NASA|access-date=September 21, 2014}}</ref><ref>{{cite journal|last1=Schirber|first1=Michael|title=Synopsis: More Dark Matter Hints from Cosmic Rays?|journal=Physical Review Letters|volume=113|issue=12|pages=121102|doi=10.1103/PhysRevLett.113.121102|pmid=25279617|year=2014|url=https://cds.cern.ch/record/1756487|arxiv=1701.07305|hdl=1721.1/90426|bibcode=2014PhRvL.113l1102A|s2cid=2585508}}</ref> A new measurement of positron fraction up to 500 GeV was reported, showing that positron fraction peaks at a maximum of about 16% of total electron+positron events, around an energy of 275 ± 32 GeV. At higher energies, up to 500 GeV, the ratio of positrons to electrons begins to fall again.

The AMS team presented for 3 days at CERN in April 2015, covering new data on 300 million proton events and helium flux.<ref>{{Cite web|title = Physics community to discuss latest results of the AMS experiment {{!}} CERN press office|url = http://press.web.cern.ch/press-releases/2015/04/physics-community-discuss-latest-results-ams-experiment|website = press.web.cern.ch|access-date = July 23, 2015}}</ref> It revealed in December 2016 that it had discovered a few signals consistent with antihelium nuclei amidst several billion helium nuclei. The result remains to be verified, and the team is currently trying to rule out possible contamination.<ref>{{cite journal |author=Sokol |first=Joshua |date=April 2017 |title=Giant space magnet may have trapped antihelium, raising idea of lingering pools of antimatter in the cosmos |url=https://www.science.org/content/article/giant-space-magnet-may-have-trapped-antihelium-raising-idea-lingering-pools-antimatter |journal=Science |doi=10.1126/science.aal1067|url-access=subscription }}</ref>

A study from 2019, using data from NASA's [[Fermi Gamma-ray Space Telescope]] discovered a halo around the nearby [[pulsar]] [[Geminga]]. The accelerated electrons and positrons collide with nearby starlight. The collision boosts the light to much higher energies. Geminga alone could be responsible for as much as 20% of the high-energy positrons seen by the AMS-02 experiment.<ref>{{Cite web|url=http://www.nasa.gov/feature/goddard/2019/nasa-s-fermi-mission-links-nearby-pulsar-s-gamma-ray-halo-to-antimatter-puzzle|title=Fermi Links Nearby Pulsar's Gamma-ray 'Halo' to Antimatter Puzzle|last=Garner|first=Rob|date=December 19, 2019|website=NASA|access-date=January 26, 2020}}</ref> The AMS-02 on the ISS has, as of 2021, recorded eight events that seem to indicate the detection of antihelium-3.<ref>{{cite journal |last1=Crane |first1=Leah |date=May 1, 2021 |title=Antimatter stars may lurk in the solar system's neighbourhood |url=https://www.newscientist.com/article/2275563-antimatter-stars-may-lurk-in-the-solar-systems-neighbourhood/ |journal=New Scientist}}</ref><ref>{{cite journal |last1=Sokol |first1=Joshua |date=April 19, 2017 |title=Giant space magnet may have trapped antihelium, raising idea of lingering pools of antimatter in the cosmos |url=https://www.science.org/content/article/giant-space-magnet-may-have-trapped-antihelium-raising-idea-lingering-pools-antimatter |journal=Science |doi=10.1126/science.aal1067|url-access=subscription }}</ref>

Over a twelve-year period aboard the ISS, the AMS has accumulated a dataset of more than 230 billion cosmic rays, spanning energies reaching multi-TeV levels. The precise measurements obtained by the magnetic spectrometer enable data presentation with an accuracy approaching ~1%. Particularly significant is the [[High-energy nuclear physics|high-energy]] data regarding elementary particles such as electrons, positrons, protons, and antiprotons, which presents challenges to theoretical frameworks. Additionally, observations of nuclei and [[isotope]]s reveal energy dependencies that deviate from theoretical predictions. In a presentation at the 2024 APS April meeting, the AMS collaboration argued that the dataset they have collected necessitates a reevaluation of existing models of the cosmos.<ref>{{Cite journal |title=APS April Meeting 2024 – Event – Latest Results from the Alpha Magnetic Spectrometer on the International Space Station |url=https://meetings.aps.org/Meeting/APR24/Session/F11.3 |journal=Bulletin of the American Physical Society |publisher=American Physical Society}}</ref>

==See also==
{{Portal|Spaceflight}}
*[[List of space telescopes]] (Astronomical Space Observatories) 
*[[Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics]] (PAMELA) – an Italian-international cosmic ray mission launched in 2006 with similar goals<!--<ref name="Hsu" />-->
*[[Scientific research on the ISS]]

==References==
{{Include-NASA|url=http://ams-02project.jsc.nasa.gov/html/Projectpage.htm|article=AMS project page}}
{{Reflist|30em|refs=
<ref name = "BBC_2013-02-18">{{cite news
  | last        = Amos
  | first       = Jonathan
  | title       = Alpha Magnetic Spectrometer to release first results
  | url         = https://www.bbc.co.uk/news/science-environment-21495800
  | publisher   = [[BBC News Online]]
  | date        = February 18, 2013
  | access-date  = February 18, 2013
}}</ref>

}}

==Further reading==
{{refbegin}}

*{{Cite journal|author=AMS Collaboration|title=Isotopic Composition of Light Nuclei in Cosmic Rays: Results from AMS-01|journal=Astrophys. J. |volume=736 |issue=2|page=105 |year=2011|arxiv = 1106.2269 |bibcode = 2011ApJ...736..105A |doi = 10.1088/0004-637X/736/2/105 |s2cid=119237635}}
*{{Cite journal|author=AMS Collaboration|title=Relative Composition and Energy Spectra of Light Nuclei in Cosmic Rays. Results from AMS-01|journal=Astrophys. J. |volume=724 |issue=1|pages=329–340 |year=2010|bibcode = 2010ApJ...724..329A |doi = 10.1088/0004-637X/724/1/329 |arxiv=1008.5051|s2cid=15550326 }}
*{{Cite journal|author=AMS Collaboration|title=Cosmic-ray positron fraction measurement from 1 to 30-GeV with AMS-01|journal=Phys. Lett. B |volume=646 |issue=4|pages=145–154 |year=2007|arxiv = astro-ph/0703154 |bibcode = 2007PhLB..646..145A |doi = 10.1016/j.physletb.2007.01.024 |s2cid=14042669}}
*{{Cite journal|author=AMS Collaboration|title=A study of cosmic-ray secondaries induced by the MIR Space Station using AMS-01|journal=Nuclear Instruments and Methods B |volume=234 |issue=3|pages=321–332 |year=2005|doi=10.1016/j.nimb.2005.01.015|bibcode=2005NIMPB.234..321A|arxiv=hep-ex/0406065|s2cid=119501638}}
*{{Cite journal|author=AMS Collaboration|title=The AMS on the ISS. Part I - Results from the test flight on the Space Shuttle|journal=Physics Reports |volume=366 |issue=6|pages=331–405 |year=2002|bibcode = 2002PhR...366..331A |doi = 10.1016/S0370-1573(02)00013-3 |s2cid=122726107 |hdl=2078.1/72661 |hdl-access=free }}
*{{Cite journal|author=AMS Collaboration|title=Helium in near Earth orbit|journal=Phys. Lett. B |volume=494 |issue=3–4|pages=193–202 |year=2000|bibcode = 2000PhLB..494..193A |doi = 10.1016/S0370-2693(00)01193-X |url=http://archive-ouverte.unige.ch/unige:44042}}
*{{Cite journal|author=AMS Collaboration|title=Cosmic Protons.|journal=Phys. Lett. B |volume=490 |issue=1–2|pages=27–35 |year=2000|bibcode = 2000PhLB..490...27A |doi = 10.1016/S0370-2693(00)00970-9 |url=http://archive-ouverte.unige.ch/unige:43952}}
*{{Cite journal|author=AMS Collaboration|title=Leptons in near earth orbit.|journal=Phys. Lett. B |volume=484 |issue=1–2|pages=10–22 |year=2000|bibcode = 2000PhLB..484...10A |doi = 10.1016/S0370-2693(00)00588-8 |url=http://hal.in2p3.fr/in2p3-00005529/file/democrite-00005529.pdf}}
*{{Cite journal|author=AMS Collaboration|title=Protons in near earth orbit.|journal=Phys. Lett. B |volume=472 |issue=1–2|pages=215–226 |year=2000|arxiv = hep-ex/0002049 |bibcode = 2000PhLB..472..215A |doi = 10.1016/S0370-2693(99)01427-6 }}
*{{Cite journal|author=AMS Collaboration|title=Search for anti-helium in cosmic rays.|journal=Phys. Lett. B |volume=461 |issue=4|pages=387–396 |year=1999|arxiv = hep-ex/0002048 |bibcode = 1999PhLB..461..387A |doi = 10.1016/S0370-2693(99)00874-6 |s2cid=119401739}}

{{refend}}

* {{Cite journal|last=Sandweiss |first=J. |date=2004|title= Overview of strangelet searches and Alpha Magnetic Spectrometer: when will we stop searching? |volume=30|issue=1 |pages=S51–S59 |doi=10.1088/0954-3899/30/1/004|journal=Journal of Physics G: Nuclear and Particle Physics|bibcode = 2004JPhG...30S..51S }}

==External links==
{{Commons category}}
* [https://ams02.space/ AMS Collaboration Homepage]
* [http://ams.cern.ch/ AMS Homepage] at [[CERN]]. Inc. construction diagrams
* [http://ams-02project.jsc.nasa.gov/index.htm AMS Homepage] {{Webarchive|url=https://web.archive.org/web/20090730145334/http://ams-02project.jsc.nasa.gov/index.htm |date=July 30, 2009 }} at the [[Johnson Space Center]]
* [https://web.archive.org/web/20090816041406/http://www.nasa.gov/mission_pages/station/science/experiments/AMS-02.html NASA AMS-02 Project Fact Sheet]
* [http://ams.nasa.gov/index.html NASA AMS-02 Project Home Page] with real-time cosmic ray count
* [http://ams-02project.jsc.nasa.gov/Videos/STS134%20no%20sound%20-2.mov An animated movie of the STS-134 mission showing the installation of AMS-02 (72&nbsp;MB)] {{Webarchive|url=https://web.archive.org/web/20110511205306/http://ams-02project.jsc.nasa.gov/Videos/STS134%20no%20sound%20-2.mov |date=May 11, 2011 }}
* [http://www.facebook.com/pages/Alpha-Magnetic-Spectrometer-AMS-02/61514694953 Alpha Magnetic Spectrometer – image collection – AMS-02 on Facebook ]
* [https://www.nytimes.com/2010/11/17/science/space/17dark.html A Costly Quest for the Dark Heart of the Cosmos (New York Times, 16 November 2010)]
* [http://www.route-to-space.eu/index.php/en/projects/alpha-magnetic-spectrometer Route To Space Alliance – European Transport for The Space and Aeronautic Industries] {{Webarchive|url=https://web.archive.org/web/20220117022853/http://www.route-to-space.eu/index.php/en/projects/alpha-magnetic-spectrometer |date=January 17, 2022 }}
*Record for [https://inspirehep.net/experiments/1401304 AMS-02] experiment on [[INSPIRE-HEP]] 
*Record for [https://inspirehep.net/experiments/1110577 AMS-01] experiment on [[INSPIRE-HEP]]

{{ISS modules}}
{{Space observatories}}
{{Dark matter}}
{{Orbital launches in 2011}}

[[Category:Particle experiments]]
[[Category:Cosmic-ray experiments]]
[[Category:Components of the International Space Station]]
[[Category:International Space Station experiments]]
[[Category:Experiments for dark matter search]]
[[Category:Spacecraft launched in 2011]]
[[Category:Space science experiments]]
[[Category:Piggyback mission]]
[[Category:CERN experiments]]