Protons in near earth orbit

• Published in: Physics letters. B 2000, Vol.472 (1), p.215-226
• Main Authors: Alcaraz, J., Ambrosi, G., Ao, L., Azzarello, P., Baldini, L., Barancourt, D., Barao, F., Barbier, G., Barreira, G., Battiston, R., Becker, R., Becker, U., Bellagamba, L., Béné, P., Bertucci, B., Boella, G., Boschini, M., Bourquin, M., Burger, J.D., Cai, X.D., Capell, M., Casaus, J., Castellini, G., Chen, H.F., Chen, H.S., Chen, Z.G., Chernoplekov, N.A., Chiarini, A., Chiueh, T.H., Commichau, V., Contin, A., Crespo, P., da Cunha, J.P., D'Antone, I., Emonet, P., Eronen, T., Esposito, G., Favier, J., Fiandrini, E., Galaktionov, Yu, Giusti, P., Grandi, D., Hofer, H., Hungerford, W., Ionica, M., Karlamaa, K., Karpinski, W., Kenney, G., Kim, W., Klimentov, A., Laborie, G., Laitinen, T., Laurenti, G., Lee, S.C., Lopes, I., Lu, G., Lustermann, W., Margotti, A., Mayet, F., Meillon, B., Menichelli, M., Mujunen, A., Pauss, F., Perrin, E., Pevsner, A., Pilastrini, R., Plyaskin, V., Postolache, V., Prati, E., Produit, N., Rancoita, P.G., Ren, D., Richeux, J.P., Roeser, U., Sagdeev, R., Sartorelli, G., Schultz von Dratzig, A., Sun, G.S., Suter, H., Ting, Samuel C.C., Ting, S.M., Tornikoski, M., Ulbricht, J., Valtonen, E., Vandenhirtz, J., Verlaat, B., Vetlitsky, I., Vezzu, F., Vialle, J.P., Vité, D., Von Gunten, H., Wang, B.C., Wang, Y.H., Wiik, K., Xia, P.C., Yan, J.L., Xu, Z.Z., Zhang, Z.P., Zhu, G.Y., Zhu, W.Z.
• Format: Article
• Language: English
• Subjects: Astrophysics; Cosmology and Extra-Galactic Astrophysics; Physics
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/S0370-2693(99)01427-6

The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380 km. Above the geomagnetic cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at equatorial latitudes with a flux ∼70 m −2 s −1 sr −1. Most of these second spectrum protons follow a complicated trajectory and originate from a restricted geographic region.