The solar activity in Cycle 23 gradually changes to final minimum phase. Sun's shadow generated by multi-TeV cosmic-ray particles has been continuously observed with the Tibet-II and Tibet-III air shower array in 1996 through 2006 during almost whole period of the Solar Cycle 23. We have shown that the Sun’s shadow is strongly affected by the solar and interplanetary magnetic fields changing with the solar activity in the previous papers. In this paper, we present yearly variation of the Sun’s shadow in association with the Solar Cycle 23. Additionally, we discuss about comparison between observation result and simulation result of Sun's shadow using the Radial Field model for the solar minimum (1996) and the maximum (2000 and 2001).

The Tibet ASgamma Collaboration

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 1 (SH), pages 529-532