See pictures in the attachment:

1) stopper seen from the back (upstream view)

2) stopper  seen from the front (downstream view)

Mind the two small off-center dots. It is clear that the beam hits the edge of the frame.  This is possible because the 5 mm collimator has two small dots outside the 5 mm hole (the collimator  can be seen in the beam tube).

3) old target, upstream view

4)  new target, upstream view, after the stopper drove into it

5) new target, before it was mounted

6) the stopper, after the collision with the target. One of the visible rings is probably due to this collision, other traces probably reflect its complicated history earlier.