The Alpha Magnetic Spectrometer on the International Space Station

March 13th XXXXth RENCONTRES DE MORIOND

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The Alpha Magnetic Spectrometer on the International Space StationCarmen Palomares CIEMAT (Madrid)On behalf of the AMS Collaboration


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AMS is a magnetic spectrometer to be installed on ISS ( 450 km)The aim of AMS is the direct detection of primary cosmic rays below the knee (NO UHECR):Determination of energy with high resolutionLarge statisticsVery good particle identification


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AMS-02 Large geometrical acceptance: 0.45 m2 sr Long exposure: 3 years Redundant measurements of the main parameters

Operational conditions: High vacuum High radiation levels Strong gradients of temperature : -60°C — +40°C Weight < 7 Tons Acceleration 3g (6g) launch (landing) Power consumption < 3 kW


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AMS GoalsAntimatter search ( ) with a sensitivity 103 better thancurrent limits

Dark matter search. Non-baryonic DM: WIMP (LSP)Signatures: e+,

High statistics study of the cosmic ray spectrum Isotope separation Antiparticle spectrum

1 year

p

He


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AMS detectorSet of sub detectors devoted to the measurement of energy and particle identification: Z, mass,…


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AMS detector

Energy ( , ) Rp

(R)/R = 1.5% for 10 GVMax. Dynamic Range 1 TV

ECAL

(E)/E ~ 3% for 100 GeV electrons

Tracker


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AMS detector

Particle Identification

Charge (Z): Tracker, ToF and RICHZ 26 (small charge confusion)Tracker + ToF sing(Z)

(Mass) :

Electron/hadron separation:TRD: p/e rejection factor 102 - 103

in the range 1.5 – 300 GeV ECAL: Hadron rejection factor 104

for E<1TeV

ToF: ()/ = 3.5% (for =1)RICH: ()/ ~ 0.1% for protons (m)/m = 2%

Test-beam results


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AMS detector status

Magnet: coils already doneToF

The sub-detectors have been tested: Test-beams at CERN using prototypes of the final detectors Qualification tests of the flight elementsCurrently, they are being assembled and qualified Integration and functional tests of the whole detector at CERN (2006)


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Galactic Cosmic Rays

The high energy CR are produced, accelerated and propagated in the Galaxy and provide information about the sources and the matter content and magneto-hydrodynamical properties of our Galaxy

Current critical measurements that can be achieved by AMS are:• Very accuracy measurements of the spectrum of H & He (R 1 TV) • Chemical abundances (from H to Fe)• The ratio of spallation products such as Boron to the primary nuclei such as Carbon as a function of energy (E 1 TeV) • The energy dependence of the fraction of antiparticles (E100GeV)• Isotopic ratios of elements (E 10 GV)


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Energy SpectrumProtons and Helium: The most abundant elements Spectral index: Origin and acceleration, differences between both speciesUsed to determine the expected fluxes of and e+ , atmospheric neutrinos, etc…

protons

Helium

p

AMS-02expectations

AMS-02expectations


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Hadrons Z>2

In addition to the information provided by primary CR such as C, N and O, secondary CR (produced by spallation) are used to estimate the amount of matter traversed by the CR(confinement volume and time)

AMS-02expectations


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Radiactive Isotopes:Provide information about the confinement time of CR in the Galaxy

10Be is specially interesting for its half time (t1/2 = 1.51 106 years)of the same order than the confinement time of the CR in the Galaxy

After 3 years, AMS will collect ~105 10Be (m)/m = 2%

AMS-02expectations


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AntiparticlesPure secondary CR from interactions with the ISM Exotic origin: A very good understanding of the expected CR fluxes

Positrons

No conclusive data

Antiprotons

Data consistent with secondary CR


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Antiparticles

AMS will measure the flux up AMS will measure the flux up

to 400 GeVto 400 GeV

After 3 years will collect After 3 years will collect 101066 p

p AMS will collect AMS will collect 101066 e e+ + and and 10107 7

ee--

These fluxes provide sensitivity to These fluxes provide sensitivity to darkdarkmatter in several scenarios matter in several scenarios

AMS-02expectations

AMS-02expectations


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• AMS will be the first large acceptance magnetic spectrometer to operate in space for a long period of time• Precise experimental measurements provided by AMS would yield information about the galactic properties, constraining propagation models• AMS will be able also to discover some evidence for new physics (dark matter) or new objects (e.g. stars made of antimatter)• Currently, AMS-02 is in the construction phase. The detector must be ready for the launch by the end of 2007

Summary


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More Slides


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Light Isotopes

1 day6 hours

D and 3He are secondary particles coming from nuclear interactions with the ISM and provide a description of the propagation of p and He

AMS-02expectations

AMS-02expectations


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Search of antimatter


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•Good understanding of GCR origin and propagation will be used to discover some evidence for new physics (dark matter) or new objects (e.g. stars made of antimatter)


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ECAL


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Ring Imaging Cerenkov Detector

Radiator (aerogel)

mirror

PMT Plane

()/ ~ 0.1% para =1

Charge determination up to Z~26


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Transition Radiation Detector

20 layers

The Alpha Magnetic Spectrometer on the International Space Station

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