04-05-2012, 12:27 PM
Radioactive Series
[attachment=21247]
Naturally occurring uranium contains more than 99% 23892U, an isotope which decays to 23490Th by α emission, as shown in Eq. (1) from Naturally Occurring Radioactivity. The product of this reaction is also radioactive, however, and undergoes β decay, as already shown in Eq. (3) from that section. The 23491Pa produced in this second reaction also emits a β particle:
Alpha Decay
The reason alpha decay occurs is because the nucleus has too many protons which cause excessive repulsion. In an attempt to reduce the repulsion, a Helium nucleus is emitted. The way it works is that the Helium nuclei are in constant collision with the walls of the nucleus and because of its energy and mass, there exists a nonzero probability of transmission. That is, an alpha particle (Helium nucleus) will tunnel out of the nucleus. Here is an example of alpha emission with americium-241:
Beta Decay
Beta decay occurs when the neutron to proton ratio is too great in the nucleus and causes instability. In basic beta decay, a neutron is turned into a proton and an electron. The electron is then emitted. Here's a diagram of beta decay with hydrogen-3:
[attachment=21247]
Naturally occurring uranium contains more than 99% 23892U, an isotope which decays to 23490Th by α emission, as shown in Eq. (1) from Naturally Occurring Radioactivity. The product of this reaction is also radioactive, however, and undergoes β decay, as already shown in Eq. (3) from that section. The 23491Pa produced in this second reaction also emits a β particle:
Alpha Decay
The reason alpha decay occurs is because the nucleus has too many protons which cause excessive repulsion. In an attempt to reduce the repulsion, a Helium nucleus is emitted. The way it works is that the Helium nuclei are in constant collision with the walls of the nucleus and because of its energy and mass, there exists a nonzero probability of transmission. That is, an alpha particle (Helium nucleus) will tunnel out of the nucleus. Here is an example of alpha emission with americium-241:
Beta Decay
Beta decay occurs when the neutron to proton ratio is too great in the nucleus and causes instability. In basic beta decay, a neutron is turned into a proton and an electron. The electron is then emitted. Here's a diagram of beta decay with hydrogen-3: