Solar Neutron Events of 2003 October–November

During the period when the Sun was intensely active on October-November 2003,two remarkable solar neutron events were observed by the ground-based neutronmonitors. On October 28, 2003, in association with an X17.2 large flare, solarneutrons were detected with high statistical significance (6.4 sigma) by theneutron monitor at Tsumeb, Namibia. On November 4, 2003, in association with anX28 class flare, relativistic solar neutrons were observed by the neutronmonitors at Haleakala in Hawaii and Mexico City, and by the solar neutrontelescope at Mauna Kea in Hawaii simultaneously. Clear excesses were observedat the same time by these detectors, with the significance calculated as 7.5sigma for Haleakala, and 5.2 sigma for Mexico City. The detector onboard theINTEGRAL satellite observed a high flux of hard X-rays and gamma-rays at thesame time in these events. By using the time profiles of the gamma-ray lines,we can explain the time profile of the neutron monitor. It appears thatneutrons were produced at the same time as the gamma-ray emission.Comment: 35 pages, 21 figures, accepted for publication in Ap