The default behavior for particles that hit a 
Static Object is to bounce off. If you want them to react in another way, you can use the 
POP Collision Detect.
Tip
If you are colliding particles with a 
Grid, turn off Use Volume Based Collision Detection on the Static Object node.
The 
POP Limit is very similar to the Collision POP, but instead of detecting collisions with geometry, it detects particles "colliding" with an imaginary boundary within a cube in 3d space. This is useful to automatically cull or bounce particles that fly too far.
The 
POP Soft Limit is like the Limit POP, but gives softer bounces. It slows particles down when they hit the boundary, giving a less jerky response than a limit or collision.
Tip
You can use a 
POP Property node to add randomization to the Mass and Bounce so that particles don’t all bounce to the same height.
Using Collision Detect
-
Create a particle system along the curve using the
Location or 
Source shelf tools. -
Create an object for the particle system to collide with.
-
Click the
Collision Detect tool on the Particles tab. -
Select the object for collision detection and press Enter.
For specific parameter help, see the
Collision Detect node help. You can choose what happens to the particles once they hit using the options on the Behavior tab.Note
Turn on Move to Hit if you want to trigger an effect from a particle’s collision. For example, if you want to birth more particles, you want the particle at the hit location, not where it ended up at the end of the frame. This will move the particle back to it’s hit location.
In the following example, particles that hit the box are sticking to it and are colored red.
Note
Standard POP collision modes support the hittotal attribute that tracks the cumulative number of hits. See the Attributes page for a full list of Collision attributes.
