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

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT 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

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT 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 dB) & acceleration (3 g ) at launch and deacceleration (6 g ) at landing Component eigenfrequency > 50 Hz Total weight < 6 T Total power consumption < 2 kW

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT 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 double- sided silicon micro-strip sensors Position with 10  m (bending) 30  m (non-bending) accuracy Rigidity precision of 1.5% for protons at 10 GV  ray measurement up to ~300 GeV by tracking e - e + pair

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT 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  =1 Charge modulus up to Z~15 Upgoing/downgoing particles at level Detector trigger

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT AMS-02 DETECTOR Ring imaging Čerenkov (RICH): silica aerogel and photomultipliers Velocity with 0.1% precision for protons with  =1 Charge modulus up to Z~26 with <10% confusion Mass determination together with rigidity measurement

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT AMS-02 DETECTOR EM calorimeter (ECAL): lead and scintillating fibers interlayed 3D sampling of cascade structure 3% energy resolution for e -, e + and  at 100 GeV Hadron rejection factor of 10 4 in 1.5 GeV – 1 TeV Standalone trigger for  ’s

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT AMS-02 DETECTOR Transition radiation detector (TRD): fiber fleece with Xe/CO 2 straw tubes Hadron rejection factor of in GeV range Anticoincidence counters

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT ANTIMATTER SEARCH Big Bang requires baryogenesis but... No evidence of large antimatter regions at less than 20 Mpc (no peaks in  -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

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT ANTIMATTER SEARCH No He has been detected yet AMS will collect 10 9 He with E  1 TeV in 3 years it will improve He sensitivity 3 to 4 orders of magnitude

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT 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 non- baryonic matter neutralino annihilations in Galactic halo would produce an excess in e +, p, D,  fluxes

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT DARK MATTER SEARCH e -, e + flux up to ~300 GeV; p flux up to ~400 GeV ~10 7 e - with E > 10 GeV, ~10 6 e + with E > 5 GeV and ~10 6 p with E > 5 GeV after 3 years on ISS

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

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT  RAY ASTROPHISICS Energy range 1 GeV – 1 TeV Energy resolution ~5% (STD), ~3% (ECAL) Angular resolution ~0.1º (STD), ~1º (ECAL)

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

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT CR MEASUREMENTS  =3.1  =2.7 Light and sub-iron elements more abundant than in Solar System Flux  E - 

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

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT CR SOURCES & ACCELERATION SNR are candidates for source and primary acceleration High energetic phenomena (~10 42 ergs -1 ) Electron synchrotron radiation observed Crab nebula Energy spectrum suggests EM acceleration mechanism Multiple reflections in a magnetised medium (Fermi, 1949) Possible in SNR shock waves

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

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

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

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

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

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT AMS-02 EXPECTATIONS AMS will precisely determine individual element fluxes with 1  Z  26 in the energy range 0.1 GeV/n  E  1 TeV/n After 3 years it will collect ~10 8 H, ~10 7 He and ~10 5 C with E > 100 GeV/n 3 days He 6 hours protons

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

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

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT AMS-02 EXPECTATIONS After 3 years it will identify ~10 4 B with E > 100 GeV/n The ratio B/C will be determined for E  1 TeV/n

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT CR PROPAGATION Confinement time and source distances from ratio unstable/stable isotopes 10 Be is the lightest isotope with half-life~1.51  10 6 years

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT AMS-02 EXPECTATIONS After 3 years, it will collect ~ Be AMS will separate 10 Be from 9 Be in the energy range 0.15 GeV/n - 10 GeV/n

ISCRA – Erice July 2004 Ana Sofía Torrentó Coello - CIEMAT 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