Solar Neutron Events in Association with Large Solar Flares in November 2003

K. Watanabe (Nagoya Univ.) for the solar neutron observation group

A series of eleven X-class solar flares were observed during October 19 and 
November 5, 2003, in NOAA regions 484, 486 and 488. Among them, in the flares 
on November 2, 3 and 4, solar neutrons were observed by the ground based 
neutron monitors and the solar neutron telescopes located around the world. 
At 17:03UT on November 2, 2003, an X8.3 class solar flare was occurred. Solar 
neutrons in association with this flare were detected by the neutron monitor 
located at Mt. Chacaltaya, Bolivia. The solar neutron event of November 3, 2003,
 was detected by the Hawaii solar neutron telescope located at Mauna Kea, in 
association with an X2.7 class flare occurred at 1:09UT. Excesses for this 
event were detected from the direction of the sun. On November 4, 2003, an 
X28 class solar flare, which is the largest flare on record, was detected at 
19:29UT. Solar neutrons were also observed by the neutron monitor at 
Mt. Haleakala, Hawaii. In these flares, intense emission of hard X-rays and 
gamma-rays have been observed by the RHESSI satellite. It seems that solar 
neutrons were produced at the same time as the production time of these hard 
electromagnetic radiations.