  Intermediate mass fragment (IMF) formation in the 12 GeV proton induced
reaction on Au target is analyzed by using a combined framework of a transport
model (JAM/MF) and a newly developed non-equilibrium percolation (NEP) model.
In this model, we can well reproduce the mass distribution of fragments. In
addition, the sideward peaked angular distribution would emerge under the
condition that the fragment formation time is very short, around 20 fm/c.
Within this short time period, the un-heated part of the residual nucleus is
kept to have doughnut shape, then the Coulomb repulsion from this shape
strengthens the sideward peak of IMF.
