  In the solar flare observed on June 3, 2012, high energy gamma-rays and
neutrons were observed. The event includes a remarkable feature of a high
neutron/gamma-ratio in the secondary particles. We have examined whether this
high n/$\gamma$-ratio can be explained by simulation. As a result of
simulations using the GEANT4 program, the high n/$\gamma$-ratio may be
reproduced for the case that helium and other heavy ions were dominantly
accelerated in the flare.
