THE AMS EXPERIMENT Ana Sofa Torrent Coello CIEMAT

THE AMS EXPERIMENT Ana Sofía Torrentó Coello – CIEMAT (Spain) On behalf of AMS Collaboration Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

PHYSICS GOALS Search for cosmic antimatter Search for dark matter signatures Deep study of cosmic ray composition and energy spectrum Gamma ray astrophysics Need of high precision and high statistics data collection Detector design Negligible background environment Long exposure time Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

DESIGN PRINCIPLES Study signals among intense backgrounds Minimum amount of material traversed Repeated measurements of momentum and velocity Safety / operational conditions on Shuttle and ISS High vacuumm conditions and radiation levels Strong temperature gradients (-60ºC to +40ºC) Vibrations (max 150 d. B) & acceleration (3 g) at launch and deacceleration (6 g) at landing Component eigenfrequency > 50 Hz Total weight < 6 T Total power consumption < 2 k. W Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

AMS-02 DETECTOR Superconducting magnet dipole field cooled down to 1. 8 K by liquid He circuit BL 2=0. 86 Tm 2 8 layers of silicon tracker (STD): 6 m 2 of doublesided silicon micro-strip sensors Position with 10 mm (bending) 30 mm (nonbending) accuracy Rigidity precision of 1. 5% for protons at 10 GV g ray measurement up to ~300 Ge. V by tracking e-e+ Ana Sofíapair Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

AMS-02 DETECTOR Time of flight (TOF) hodoscopes: 4 planes of scintillators Time of flight with ~120 ps resolution 3. 5% accuracy in velocity for particles with b=1 Charge modulus up to Z~15 Upgoing/downgoing particles at 10 -8 level Detector trigger Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

AMS-02 DETECTOR Ring imaging Čerenkov (RICH): silica aerogel and photomultipliers Velocity with 0. 1% precision for protons with b=1 Charge modulus up to Z~26 with <10% confusion Mass determination together with rigidity measurement Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

AMS-02 DETECTOR EM calorimeter (ECAL): lead and scintillating fibers interlayed 3 D sampling of cascade structure 3% energy resolution for e-, e+ and g at 100 Ge. V Hadron rejection factor of 104 in 1. 5 Ge. V – 1 Te. V Standalone trigger for Ana Sofíag’s Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

AMS-02 DETECTOR Transition radiation detector (TRD): fiber fleece with Xe/CO 2 straw tubes Hadron rejection factor of 102 -103 in 1. 5 -300 Ge. V range Anticoincidence counters Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

ANTIMATTER SEARCH Big Bang requires baryogenesis but. . . No evidence of large antimatter regions at less than 20 Mpc (no peaks in g-ray diffuse background from annihilation) Baryon number and strong C and CP violation not observed yet Positrons and antiprotons are widely produced in ISM but. . . heavier antinuclei (He, C, . . . ) could only be produced in antistars search for antinuclei in cosmic ray flux Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

ANTIMATTER SEARCH No He has been detected yet AMS will collect 109 He with E 1 Te. V in 3 years it will improve He sensitivity 3 to 4 orders of magnitude Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

DARK MATTER SEARCH Observational evidence of large amount of non-luminous matter in the Universe. . . Stellar populations + other baryonic objects (brown dwarfs, MACHOs, . . . ) are not numerous and/or massive enough to hold all the missing matter SUSY extensions of SM propose nonbaryonic matter neutralino annihilations in Galactic halo would produce an excess in e+, p, D, g fluxes Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

DARK MATTER SEARCH e-, e+ flux up to ~300 Ge. V; p flux up to ~400 Ge. V ~107 e- with E > 10 Ge. V, ~106 e+ with E > 5 Ge. V and ~106 p with E > 5 Ge. V after 3 years on ISS Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

g RAY ASTROPHISICS AMS will contribute to the study of g diffuse background, both galactic and extragalactic g source location Dark matter search through c annihilation Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

g RAY ASTROPHISICS Energy range 1 Ge. V – 1 Te. V Energy resolution ~5% (STD), ~3% (ECAL) Angular resolution ~0. 1º (STD), ~1º (ECAL) Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

COSMIC RAYS Charged particles arriving in Earth from the Sun, our galaxy and other galaxies Mainly protons (90%) and alpha particles (9%) Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR MEASUREMENTS • Flux E-g g=2. 7 g=3. 1 Light and sub-iron elements more abundant than in Solar System Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR “LIFE STORY” Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR SOURCES & ACCELERATION SNR are candidates for source and primary acceleration Crab nebula High energetic phenomena (~1042 ergs-1) Electron synchrotron radiation observed Energy spectrum suggests EM acceleration mechanism Multiple reflections in a magnetised medium (Fermi, 1949) Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004 Possible in SNR shock waves

CR PRIMARY SPECIES Primary species (H, He, nucleosynthesis) abundances are related to source composition and injection spectra Strong-Moskalenko 1998 Same with different gas distribution Ana Sofía Torrentó Coello - CIEMAT constraint in source type and primary acceleration mechanisms ISCRA – Erice. 2 -13 July 2004

CR PRIMARY SPECIES Engelman (1990) Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR PRIMARY SPECIES Engelman (1990) Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR PRIMARY SPECIES Engelman (1990) Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR PRIMARY SPECIES Engelman (1990) Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

AMS-02 EXPECTATIONS protons 6 hours He 3 days AMS will precisely determine individual element fluxes with 1 Z 26 in the energy range 0. 1 Ge. V/n E 1 Te. V/n After 3 years it will collect ~108 H, ~107 He and ~105 C with E > 100 Ge. V/n Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR PROPAGATION Diffusion within the ISM: Energy loss by ionization or diffusion Disintegration Spallation Radioactive decay Reacceleration Escape Solar modulation Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR PROPAGATION Secondary particle spectrum and ratio of secondary to primary Constraint on propagation models: diffusion parameter, halo size, reacceleration Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

AMS-02 EXPECTATIONS After 3 years it will identify ~104 B with E > 100 Ge. V/n The ratio B/C will be determined for E 1 Te. V/n Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

CR PROPAGATION Confinement time and source distances from ratio unstable/stable isotopes 10 Be is the lightest isotope with half-life~1. 51 106 years Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

AMS-02 EXPECTATIONS After 3 years, it will collect ~105 10 Be AMS will separate 10 Be from 9 Be in the energy range 0. 15 Ge. V/n - 10 Ge. V/n Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004

SUMMARY AMS will be the first large acceptance magnetic spectrometer to operate in a background-free environment for a long period of time It will perform a long term search for antimatter and dark matter It will also perform precise measurements of galactic CR elemental and isotopic composition and energy spectra validate current models for galactic cosmic ray propagation Ana Sofía Torrentó Coello - CIEMAT ISCRA – Erice. 2 -13 July 2004