They will penetrate about 8 mm into the body. Bremsstrahlung One important characteristic of beta radiation is that as the beta particles pass through materials they can produce secondary radiations, called Bremsstrahlung x-rays. The probability that this will happen is greatest with high energy betas and high atomic number materials such as lead. The other common types of ionizing radiation from the radioactive decay process are gamma rays and x-ray photons. Gamma rays are nuclear in origin while x-rays are generated outside the nucleus.
Photons have no mass or charge, but are electromagnetic, as are light, uv, and radio waves.
Since photons have no mass or charge, they interact in a different manner than do particles like the beta. Photons travel through medium without interaction until they undergo a chance encounter. As a result, every gamma has a finite probability of passing all the way through a medium. Theoretically, a photon could go on forever - but most are absorbed in moderate amounts of shielding materials. An example of a photon emitters in the lab is Cr-51.