The Alpha Magnetic Spectrometer on the International Space

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

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 March 13 th XXXXth RENCONTRES DE 2 MORIOND Very good particle identification

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 Tons § Acceleration 3 g (6 g) launch (landing) § Power consumption < 3 k. W March 13 th XXXXth RENCONTRES DE MORIOND 3

AMS Goals Antimatter search ( ) with a sensitivity 103 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 13 th XXXXth RENCONTRES DE MORIOND 4

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

AMS detector Energy ( , ) Tracker (R)/R = 1. 5% for 10 GV Max. Dynamic Range 1 TV ECAL (E)/E ~ 3% for 100 Ge. V electrons March 13 th XXXXth RENCONTRES DE MORIOND 6

AMS detector Particle Identification Charge (Z): Tracker, To. F and RICH Z 26 (small charge confusion) Tracker + To. F sing(Z) Electron/hadron separation: TRD: p/e rejection factor 102 - 103 in the range 1. 5 – 300 Ge. V ECAL: Hadron rejection factor 104 for E<1 Te. V Test-beam results (Mass) : To. F: ( )/ = 3. 5% (for =1) RICH: ( )/ ~ 0. 1% for protons March 13 th XXXXth RENCONTRES DE (m)/m = 2% MORIOND 7

AMS detector status The sub-detectors have been tested: § Test-beams at CERN using prototypes of the final detectors § Qualification tests of the flight elements Currently, they are being assembled and qualified Integration and functional tests of the whole detector at CERN (2006) Magnet: coils already done March 13 th To. F XXXXth 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 magnetohydrodynamical 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 Te. V) • The energy dependence of the fraction of antiparticles (E 100 Ge. V) • Isotopic ratios of elements (E 10 GV) March 13 th XXXXth 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 AMS-02 expectations Helium AMS-02 expectations March 13 th XXXXth 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 13 th XXXXth RENCONTRES DE MORIOND 11

Radiactive Isotopes: Provide information about the confinement time of CR in the Galaxy 10 Be is specially interesting for its half time (t 1/2 = 1. 51 106 years) of the same order than the confinement time of the CR in the Galaxy AMS-02 expectations Ø After 3 years, AMS will collect ~105 10 Be Ø (m)/m = 2% March 13 th XXXXth RENCONTRES DE MORIOND 12

Antiparticles Pure secondary CR from interactions with the ISM Exotic origin: A very good understanding of the expected CR fluxes Antiprotons Positrons Data consistent with secondary CR March 13 th XXXXth RENCONTRES DE MORIOND No conclusive data 13

Antiparticles AMS will measure the flux up to 400 Ge. V After 3 years will collect 106 AMS will collect 106 e+ and 107 e. These fluxes provide sensitivity to dark matter in several scenarios AMS-02 expectations March 13 th XXXXth RENCONTRES DE MORIOND 14

Summary • 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 March 13 th XXXXth RENCONTRES DE MORIOND 15

More Slides March 13 th XXXXth RENCONTRES DE MORIOND 16

Light Isotopes 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 6 hours 1 day AMS-02 expectations March 13 th XXXXth RENCONTRES DE MORIOND 17

Search of antimatter March 13 th XXXXth RENCONTRES DE MORIOND 18

• 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) March 13 th XXXXth RENCONTRES DE MORIOND 19

ECAL March 13 th XXXXth RENCONTRES DE MORIOND 20

Ring Imaging Cerenkov Detector Radiator (aerogel) ( )/ ~ 0. 1% para =1 Charge determination up to Z~26 mirror PMT Plane March 13 th XXXXth RENCONTRES DE MORIOND 21

Transition Radiation Detector 20 layers March 13 th XXXXth RENCONTRES DE MORIOND 22