Get position and velocity of particle system object

Hi everyone. I found a document to simulate particle system link
I also found a source code to create a particle system object in isaac_sim-2023.1.1/extsPhysics/omni.physx.demos-105.1.12-5.1/omni/physxdemos/scenes/
This is the code of class ParticleClothDemo and I was successful to use this class to make a particle system object.

I want to get the position and velocity of this object but I still cannot find the way.

Can you help me please !
Thank you so much !