Maximum penetrating radiation among the below is
The penetrating power of alpha rays, beta rays, and gamma rays varies greatly. Alpha paicles can be blocked by a few pieces of paper. Beta paicles pass through paper but are stopped by aluminium foil. Gamma rays are the most difficult to stop and require concrete, lead, or other heavy shielding to block them.Reference: Eric J Hall Textbook of Radiobiology for Radiologist; 5th edition
Electrons
Gamma rays
Alpha paicles
Beta paicles
Radiotherapy