Knowledge of the rigidity dependence of the boron to carbon flux ratio (B/C) is important in understanding the propagation of cosmic rays. The precise measurement of the B/C ratio from 1.9 GV to 2.6 TV, based on 2.3 million boron and 8.3 million carbon nuclei collected by AMS during the first 5 years of operation, is presented. The detailed variation with rigidity of the B/C spectral index is reported for the first time. The B/C ratio does not show any significant structures in contrast to many cosmic ray models that require such structures at high rigidities. Remarkably, above 65 GV, the B/C ratio is well described by a single power law R. with index. Delta = -0.333 +/- 0.014(fit) +/- 0.005(syst), in good agreement with the Kolmogorov theory of turbulence which predicts. Delta = -1/3 asymptotically.

Knowledge of the precise rigidity dependence of the helium flux is important in understanding the origin, acceleration, and propagation of cosmic rays. A precise measurement of the helium flux in primary cosmic rays with rigidity (momentum/charge) from 1.9 GV to 3 TV based on 50 million events is presented and compared to the proton flux. The detailed variation with rigidity of the helium flux spectral index is presented for the first time. The spectral index progressively hardens at rigidities larger than 100 GV. The rigidity dependence of the helium flux spectral index is similar to that of the proton spectral index though the magnitudes are different. Remarkably, the spectral index of the proton to helium flux ratio increases with rigidity up to 45 GV and then becomes constant; the flux ratio above 45 GV is well described by a single power law.

A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.

We present a precise measurement of the combined electron plus positron flux from 0.5 GeV to 1 TeV, based on the analysis of the data collected by the Alpha Magnetic Spectrometer during the first 30 months of operations aboard the International Space Station. The statistics and the high resolution of AMS-02 detector provide a precise measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the combined electron plus positron flux can be described accurately by a single power law.

The AMS-02 Magnetic Spectrometer is a state-of-the art particle physics detector operating as an external module on the International Space Station. The purpose of the experiment is to study with unprecedented level of statistics the fluxes of cosmic rays in an energy range from 0.5 GeV to few TeV. The Silicon Tracker system accurately determines the trajectory and absolute electric charge of cosmic rays by multiple measurements of the coordinates and energy loss. It is composed of 2284 double-sided silicon micro-strip detectors arranged in nine layers. A charged particle traversing the silicon volume looses energy through ionization. This energy loss is proportional to the square of the particle charge thus allowing the distinction between different nuclei. The analog readout and the high dynamic range of the front end electronics allow to identify nuclear species from hydrogen up to iron and above. The charge resolution is naturally degraded by a number of detector effects that need to be correctly accounted for. In-flight calibration of the Tracker is done using the statistics accumulated during two years of operation in space, allowing to perform a precise equalization and linearization of the responses of the 3072 amplifier chips. This results in an excellent overall charge discrimination power. In this contribution we describe the Tracker system and the main challenges of its operation in space. We then present the procedure that has been used to accurately calibrate the Tracker's response and optimize its performances in terms of charge resolution.

M. Aguilar, D. Aisa, B. Alpat, A. Alvino, G. Ambrosi, K. Andeen, L. Arruda, N. Attig, P. Azzarello, A. Bachlechner, F. Barao, A. Barrau, L. Barrin, A. Bartoloni, L. Basara, M. Battarbee, R. Battiston, J. Bazo, U. Becker, M. Behlmann, B. Beischer, J. Berdugo, B. Bertucci, G. Bigongiari, V. Bindi, S. Bizzaglia, M. Bizzarri, G. Boella, W. de Boer, K. Bollweg, V. Bonnivard, B. Borgia, S. Borsini, M. J. Boschini, M. Bourquin, J. Burger, F. Cadoux, X. D. Cai, M. Capell, S. Caroff, J. Casaus, V. Cascioli, G. Castellini, I. Cernuda, F. Cervelli, M. J. Chae, Y. H. Chang, A. I. Chen, H. Chen, G. M. Cheng, H. S. Chen, L. Cheng, A. Chikanian, H. Y. Chou, E. Choumilov, V. Choutko, C. H. Chung, C. Clark, R. Clavero, G. Coignet, C. Consolandi, A. Contin, C. Corti, B. Coste, M. Crispoltoni, Z. Cui, M. Dai, C. Delgado, S. Della Torre, M. B. Demirköz, L. Derome, S. Di Falco, L. Di Masso, F. Dimiccoli, C. Díaz, P. von Doetinchem, F. Donnini, W. J. Du, M. Duranti, D. D’Urso, A. Eline, F. J. Eppling, T. Eronen, Y. Y. Fan, L. Farnesini, J. Feng, E. Fiandrini, A. Fiasson, E. Finch, P. Fisher, Y. Galaktionov, G. Gallucci, B. García, R. García-López, C. Gargiulo, H. Gast, I. Gebauer, M. Gervasi, A. Ghelfi, W. Gillard, F. Giovacchini, P. Goglov, J. Gong, C. Goy, V. Grabski, D. Grandi, M. Graziani, C. Guandalini, I. Guerri, K. H. Guo, M. Habiby, S. Haino, K. C. Han, Z. H. He, M. Heil, J. Hoffman, T. H. Hsieh, Z. C. Huang, C. Huh, M. Incagli, M. Ionica, W. Y. Jang, H. Jinchi, K. Kanishev, G. N. Kim, K. S. Kim, Th. Kirn, R. Kossakowski, O. Kounina, A. Kounine, V. Koutsenko, M. S. Krafczyk, S. Kunz, G. La Vacca, E. Laudi, G. Laurenti, I. Lazzizzera, A. Lebedev, H. T. Lee, S. C. Lee, C. Leluc, H. L. Li, J. Q. Li, Q. Li, Q. Li, T. X. Li, W. Li, Y. Li, Z. H. Li, Z. Y. Li, S. Lim, C. H. Lin, P. Lipari, T. Lippert, D. Liu, H. Liu, T. Lomtadze, M. J. Lu, Y. S. Lu, K. Luebelsmeyer, F. Luo, J. Z. Luo, S. S. Lv, R. Majka, A. Malinin, C. Mañá, J. Marín, T. Martin, G. Martínez, N. Masi, D. Maurin, A. Menchaca-Rocha, Q. Meng, D. C. Mo, L. Morescalchi, P. Mott, M. Müller, J. Q. Ni, N. Nikonov, F. Nozzoli, P. Nunes, A. Obermeier, A. Oliva, M. Orcinha, F. Palmonari, C. Palomares, M. Paniccia, A. Papi, M. Pauluzzi, E. Pedreschi, S. Pensotti, R. Pereira, F. Pilo, A. Piluso, C. Pizzolotto, V. Plyaskin, M. Pohl, V. Poireau, E. Postaci, A. Putze, L. Quadrani, X. M. Qi, T. Räihä, P. G. Rancoita, D. Rapin, J. S. Ricol, I. Rodríguez, S. Rosier-Lees, A. Rozhkov, D. Rozza, R. Sagdeev, J. Sandweiss, P. Saouter, C. Sbarra, S. Schael, S. M. Schmidt, D. Schuckardt, A. Schulz von Dratzig, G. Schwering, G. Scolieri, E. S. Seo, B. S. Shan, Y. H. Shan, J. Y. Shi, X. Y. Shi, Y. M. Shi, T. Siedenburg, D. Son, F. Spada, F. Spinella, W. Sun, W. H. Sun, M. Tacconi, C. P. Tang, X.W. Tang, Z. C. Tang, L. Tao, D. Tescaro, Samuel C. C. Ting, S. M. Ting, N. Tomassetti, J. Torsti, C. Türkoğlu, T. Urban, V. Vagelli, E. Valente, C. Vannini, E. Valtonen, S. Vaurynovich, M. Vecchi, M. Velasco, J. P. Vialle, L. Q. Wang, Q. L. Wang, R. S. Wang, X. Wang, Z. X. Wang, Z. L. Weng, K. Whitman, J. Wienkenhöver, H. Wu, X. Xia, M. Xie, S. Xie, R. Q. Xiong, G. M. Xin, N. S. Xu, W. Xu, Q. Yan, J. Yang, M. Yang, Q. H. Ye, H. Yi, Y. J. Yu, Z. Q. Yu, S. Zeissler, J. H. Zhang, M. T. Zhang, X. B. Zhang, Z. Zhang, Z. M. Zheng, H. L. Zhuang, V. Zhukov, A. Zichichi, N. Zimmermann, P. Zuccon, C. Zurbach

A precision measurement by AMS of the positron fraction in primary cosmic rays in the energy range from 0.5 to 500 GeV based on 10.9 million positron and electron events is presented. This measurement extends the energy range of our previous observation and increases its precision. The new results show, for the first time, that above ∼200  GeV the positron fraction no longer exhibits an increase with energy.

A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6 : 8 (cid:1) 10 6 positron and electron events is presented. The very accurate data show that the positron

A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 × 10(6) positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ∼ 250  GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.

The Alpha Magnetic Spectrometer 02 is a particle detector taking data on the International Space Station since May 19th 2011. A key element of AMS-02 is the Silicon Tracker that allows to determine the trajectory of the charged cosmic rays passing through the AMS-02 magnetic field. In this contribution, we discuss the procedures that from the tracker raw signals allow to reconstruct a full particle trajectory. We discuss how different fitting procedures achieve the best rigidity measurement accuracy in different intervals and we present the overall performance in the rigidity measurement for protons and helium nuclei. Finally we present a technique to reduce the charge confusion.

The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper we present measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be) and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.

Aims. HESS J1632-478 is an extended and still unidentified TeV source in the galactic plane.Methods. In order to identify the source of the very high energy emission and to constrain its spectral energy distribution, we used a deep observation of the field obtained with XMM-Newton together with data from Molonglo, Spitzer and Fermi to detect counterparts at other wavelengths.Results. The flux density emitted by HESS J1632-478 peaks at very high energies and is more than 20 times weaker at all other wavelengths probed. The source spectrum features two large prominent bumps with the synchrotron emission peaking in the ultraviolet and the external inverse Compton emission peaking in the TeV. HESS J1632-478 is an energetic pulsar wind nebula with an age of the order of 104 years. Its bolometric (mostly GeV-TeV) luminosity reaches 10% of the current pulsar spin down power. The synchrotron nebula has a size of 1 pc and contains an unresolved point-like X-ray source, probably the pulsar with its wind termination shock.