Gamma radiation penetration depth half value layer
The interactions of the various radiations with matter are unique and determine their penetrability through matter and, consequently, the type and amount of shielding needed for radiation protection. Being electrically neutral, the interaction of gamma rays with matter is a statistical process and depends on the nature of the absorber as well as the energy of the gamma. There is always a finite probability for a gamma to penetrate a given thickness of absorbing material and so, unlike the charged particulate radiations which have a maximum range in the absorber where all are stopped regardless of source strength, some gammas will always get through and, given a strong enough source, a lot may get through. This demo is usually presented in conjunction with the Sources and Detection demo; details about the radionuclides and detectors used here can also be found in that writeup. The range of alphas of a given energy is a fairly unique quantity in a specific absorber material.