Questions about radioactive

1. Alpha ray is a kind of "corpuscular radiation". That is to say, it is a beam of particles. These particles are called "alpha particles".

Alpha particles consist of two positive electronic charges. In the actual fact, an Alpha particle is the nucleus of a helium-4 atom, i.e. consists of two protons and two neutrons.

2. When gamma ray enters into matter, depending on the gamma ray energy, it will interact with atoms in the matter and lose energy by one of the three interaction processes. These three processes are: photoelectric effect, Compton scattering and pair-production. For detailed description of each of these processes, please refer to my earlier answer,

http://hk.knowledge.yahoo.com/question/question?qid=7008112201436

Through these processes, the incident gamma ray loses it energy until it is completley absorbed.

Human tissues also interact with gamma rays by the above described processes. However, it should be noted that these are physical processes that gamma ray interacts with human oragn tissues. If such processes happen within the nuclei of body cells, ions and/or electrons produced by the interaction processes could damage the affected cells, especially the DNA in the cells, thus leading to various ill effects, such as the development of cancer.