The heated neut particle creates a burn mark at the beginning which is supposed to happen and so the neut particle should have cooled down however at the opposite end of the wood it creates a trail too although less-burned.
NEUT usually displaces WOOD (pulled back), since this NEUT is so fast and coming from INVS, the WOOD can't go back, so apparently the first WOOD it hits is carried all the way to the end.
You can see this better by drawing some GOO anywhere to the right, you'll see WOOD appear in the GOO, with GOO going back through the block.