A quasistationary state is defined as a long-lived state that eventually decays. They assumed that the alpha particle and the daughter nucleus exist within the parent nucleus prior to its dissociation, namely the decay of quasistationary states (QS). On the other hand, a 5 MeV alpha particle bound in a nuclear potential well is able to tunnel that same Coulomb barrier.īy 1928, George Gamow (and independently by Ronald Gurney and Edward Condon) had solved the theory of alpha decay via quantum tunneling. On the one hand an incoming 5 MeV alpha particle is scattered from a heavy nucleus and it cannot penetrate the Coulomb barrier and get sufficiently close to the nucleus to interact via the strong force. The alpha particles emitted in nuclear decay have typical energies of about 5 MeV. The height of the Coulomb barrier for nuclei of A « 200 is about 20-25 MeV. This is similar to cluster decay, in which an atomic nucleus emits a small “cluster” of neutrons and protons (e.g. In order to be emitted, the alpha particle must penetrate a potential barrier. The alpha decay channel in heavy and super heavy nuclei has provided information on the fundamental properties of nuclei far from stability, such as their ground state energies and the structure of their nuclear levels.Īlpha decay is a quantum tunneling process. Theory of Alpha Decay – Quantum TunnelingĪmong the variety of channels in which a nucleus decays, alpha decay has been one of the most studied. Alpha particles are commonly emitted by all of the heavy radioactive nuclei occuring in the nature ( uranium, thorium or radium), as well as the transuranic elements (neptunium, plutonium or americium). In nuclear reactors alpha decay occurs for example in the fuel (alpha decay of heavy nuclei). In practice, this mode of decay has only been observed in nuclides considerably heavier than nickel, with the lightest known alpha emitters being the lightest isotopes (mass numbers 106–110) of tellurium (element 52). They travel only a few centimeters but deposit all their energies along their short paths.
![alpha decay alpha decay](https://image.slideserve.com/242969/alpha-decay-l.jpg)
They are not very penetrating and a piece of paper can stop them.
![alpha decay alpha decay](http://image1.slideserve.com/2338523/alpha-decay-n.jpg)
Alpha particles are relatively large and carry a double positive charge. Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. Alpha particles are energetic nuclei of helium. This transition can be characterized as:Īs can be seen from the figure, alpha particle is emitted in alpha decay. Alpha decay (or α-decay and also alpha radioactivity) represents the disintegration of a parent nucleus to a daughter through the emission of the nucleus of a helium atom.