Neutral particles that are of interest in the field of radioactivity are gamma photons, neutrons produced in the core of nuclear reactors and neutrinos. They do not ionize and do not lose their energy gradually. On the other hand, to transmit their energy to the medium they can interact or set in motion other particles.
Gamma photons interact essentially with the electrical charges of atoms.
Neutrons are nucleons that do not feel these electric charges but can be captured by nuclei and trigger nuclear reactions such as nuclear fission.
Neutrinos are so weakly interacting that they are very difficult to detect. Practically invisible, they have a negligible effect on matter and it is therefore so easy to protect ourselves from them that we can ignore their existence..
Once these electrons start moving, they lose their energy and slow down like any other charged particle. Somehow, a gamma photon outsources to these particles set in motion the task of transferring its energy to the medium. Not very localized (and therefore highly diffuse in space), it is impossible to predict where the transfer of energy will take place contrarily to the case of alpha or beta particles.
Still more unpredictable is the path of a neutron, the way in which it slows down and loses its energy. A neutron completely ignores the electrons it passes, interacting only with nuclear matter. It transfer its energy by knocking nuclei and setting them in motion. It can also be captured by nuclei, often inducing nuclear reactions. After capturing one neutron, stable nuclei may become radioactive.
Access to page in french