March 13thXXXXth RENCONTRES DE MORIOND 1 The Alpha Magnetic Spectrometer on the International Space Station Carmen Palomares CIEMAT (Madrid) On behalf of the AMS Collaboration

March 13thXXXXth RENCONTRES DE MORIOND 2 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 resolution Large statistics Very good particle identification

March 13thXXXXth RENCONTRES DE MORIOND 3 AMS-02  Large geometrical acceptance: 0.45 m 2 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 Tm  Acceleration 3g (6g) launch (landing)  Power consumption < 2 kW

March 13thXXXXth RENCONTRES DE MORIOND 4 AMS Goals Antimatter search ( ) with a sensitivity 10 3 better than current 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

March 13thXXXXth RENCONTRES DE MORIOND 5 AMS detector Set of sub detectors devoted to the measurement of energy and particle identification: Z, mass,…

March 13thXXXXth RENCONTRES DE MORIOND 6 AMS detector Energy (, )  (p)/p = 1.5% for 10 GeV ECAL Max. Dynamic Range 1 TeV/n  (E)/E ~ 3% for 100 GeV electrons Tracker

March 13thXXXXth RENCONTRES DE MORIOND 7 AMS detector Particle Identification Charge (Z): Tracker sign(Z), ToF and RICH Z  26 (small charge confusion)  (Mass) : Electron/hadron separation: TRD: p/e rejection factor in the range 1.5 – 300 GeV ECAL: Hadron rejection factor 10 4 for E<1TeV ToF:  (  )/  = 3.5% (for  =1) RICH:  (  )/  ~ 0.1% for protons  (m)/m = 2%

March 13thXXXXth RENCONTRES DE MORIOND 8 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 (E  100GeV) Isotopic ratios of elements (E  10 GV) Measurements unreachable by AMS: Chemical composition near and beyond the knee

March 13thXXXXth RENCONTRES DE MORIOND 9 Energy Spectrum Protons and Helium: The most abundant elements Spectral index: Origin and acceleration, differences between both species Used to determine the expected fluxes of and e +, atmospheric neutrinos, etc… protons Helium AMS-02 expectations AMS-02 expectations

March 13thXXXXth RENCONTRES DE MORIOND 10 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-02 expectations

March 13thXXXXth RENCONTRES DE MORIOND 11 Radiactive Isotopes: Provide information about the confinement time of CR in the Galaxy 10 Be is specially interesting because of its half time (t 1/2 = years) is of the same order than the confinement time of the CR in the Galaxy  After 3 years, AMS will collect ~ Be   (m)/m = 2% AMS-02 expectations

March 13thXXXXth RENCONTRES DE MORIOND 12 Antiparticles Pure 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

March 13thXXXXth RENCONTRES DE MORIOND 13 Antiparticles AMS will measure the flux up to 400 GeV After 3 years will collect  10 6 AMS will collect  10 6 e + and  10 7 e - These fluxes will allow to find out dark matter AMS-02 expectations AMS-02 expectations

March 13thXXXXth RENCONTRES DE MORIOND 14 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

March 13thXXXXth RENCONTRES DE MORIOND 15 More Slides

March 13thXXXXth RENCONTRES DE MORIOND 16 Light Isotopes 1 day 6 hours D and 3 He are secondary particles coming from nuclear interactions with the ISM and provide a description of the propagation of p and He AMS-02 expectations AMS-02 expectations

March 13thXXXXth RENCONTRES DE MORIOND 17 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)