Radioactivity α
The radioactivity alpha (or alpha radiation, symbolized α) is a form of radioactive disintegration where a Atomic nucleus ejects a Particule alpha and is transformed into a core of Mass number decreased of 4 and Atomic number decreased of 2 :
where represents the Mass number, the Atomic number.
The disintegration of the uranium 238 écrit :
It can be specified in the form:
Indeed the particle alpha is a core of Hélium and disintegration preserves well the full number of nucleons and the total electric charge.
Another example running, the disintegration of the Radium which is transformed into Radon :
The decay alpha can be seen as a form of Nuclear fission where the core father is divided into two cores wire.
At the energy level, disintegration α presents a spectrum of line, signature of the difference of the masses of the cores father and wire. In particular, the same core father can (statistically) lead to the core wire in different states: its fundamental, or one of its excited states.
The particles α very generally show a weak kinetic energy (compared to the energy of mass of the particle α), values lower than 10 MeV: they are thus not relativists. This fact, associated with their characteristic of particles charged (Z=2), confers a weak penetration to them (a few centimetres in the air).
It quickly appeared a remarkable bond between the supplied energy of the reaction (practically, kinetic energy of the particle α) and the radioactive Half-life of the core father: the periods are all the more large as the supplied energy is small. This observation led to an interpretation of disintegration like due to a Tunnel effect between the well of intranuclear potential and the outside of the Coulomb barrier of potential existing between the two final cores; this constitutes the base of the model of Gamow.
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