Y. Muraki

Solar-Terrestrial Environment Laboratory, Nagoya university, Nagoya, 464-8601, Japan

In association with the solar flare of November 28th 1998 (GOES X-class was X=3.3), solar neutrons are possibly detected by a new neutron telescope located at Yangbating (4300m a.s.l) in Tibet. The time profile of this event was examined by a Monte Carlo simulation. If we assume that neutrons were produced with a hard spectrum at 5h32m30s UT, the ten seconds time profile of this event can be explained well. Although detail simulations are necessary to affirm neutron observation, however this is first evidence that solar neutrons are detected at large solar flares, but less than X<8. An interesting feature of this event is seen that ions were accelerated faster than electrons. In the conference, we present combined results of Yokoh, Nobeyama Heliograph and Mitaka magnetometer, together with Monte Carlo results.