alpha, beta, gamma
X-rays and Gamma rays are the two most penetrating rays in the electromagnetic spectrum.
The most penetrating X-rays are the highest frequency (shortest wavelength) X-rays. They are the most energetic, and we sometimes refer to them as hard X-rays.
The most penetrating power is for beta particles compared to those given here.
gamma
the neutrino
gamma
The gamma radiation is extremely penetrant.
Of all the three types of radiation (alpha, beta and gamma), Gamma rays are the most penetrating, being able to travel through a few meters of lead.
Gamma radiation
Gamma rays are by far the most penetrating of the three types of radiation.
The sound was so penetrating it hurt my ears. There was so much blood, it was penetrating the bandage. The troop was penetrating enemy lines. Sarah Palin's voice is penetrating and grating on my ears.