The Cosmic Ray Shadows of the Moon and the Sun Detected by the Milagro Gamma Ray Observatory

摘要

The Milagro gamma ray observatory has operated since June,1999 which spans the solar activity maximum of the 23rd solar cycle (in 2000).An analysis of the data shows that the shadows of the sun and moon have each been detected with high significances by observing cosmic-ray deficits from these directions.In the current Milagro measurement the shadow of the sun is significantly weaker than that of the moon.As expected,the measured positions of the deficits differ from the nominal positions of these objects due to cosmic-ray bending in the magnetic fields of the earth and the sun.The different displacements of the shadows of the sun in the "away" and "toward" sectors of the interplanetary magnetic field(IMF) are consistent with no shift of the shadow given the statistical uncertainty in the measurement.The result of this analysis will be presented.