According to the comments :
This is an alpha radiation source. So its shooting off what amounts to helium nuclei (2 protons and 2 neutrons) at high-speeds. Alpha particles are large, so they hit other nuclei often and come to a stop quickly. Their range in air is typically 10cm or less. As the camera sensor gets within this range, more and more of the high-speed particles hit the sensor and cause the elements to activate. Which is what you see here. Alphas cant penetrate skin (too big), so its safe for this guy to be handling it the way he is. The only way alphas are really bad for you is if you get the source material inside you. Ingestion, injection, or inhalation where it can irradiate you from the inside.
There are other types of radiation: beta (electron emission, range of 1 meter in air), photon emission (gamma, x-ray), and neutron emission. Gammas and neutrons are the gnarly ones that go a distance and cause nuclear reactions and whatnot.
This is an alpha radiation source. So its shooting off what amounts to helium nuclei (2 protons and 2 neutrons) at high-speeds. Alpha particles are large, so they hit other nuclei often and come to a stop quickly. Their range in air is typically 10cm or less. As the camera sensor gets within this range, more and more of the high-speed particles hit the sensor and cause the elements to activate. Which is what you see here. Alphas cant penetrate skin (too big), so its safe for this guy to be handling it the way he is. The only way alphas are really bad for you is if you get the source material inside you. Ingestion, injection, or inhalation where it can irradiate you from the inside.
There are other types of radiation: beta (electron emission, range of 1 meter in air), photon emission (gamma, x-ray), and neutron emission. Gammas and neutrons are the gnarly ones that go a distance and cause nuclear reactions and whatnot.
