Alpha decay helium produced on Earth is the result of the alpha decay of underground deposits of minerals containing uranium or thorium. The helium is brought to the surface as a by-product of natural gas production. Alpha particles were first described in the investigations of radioactivity by Ernest Rutherford in 1899, and by 1907 they were identified as He ions. By 1928, George Gamow had solved the theory of alpha decay via tunneling. The alpha particle is trapped in a potential well by the nucleus. Classically, it is forbidden to escape, but according to the (then) newly discovered principles of quantum mechanics,
Isotopes of nitrogen isotopes of carbon, while most of the isotopes with masses above 15 decay to isotopes of oxygen. The shortest-lived known isotope is nitrogen-10, with a half-life of about 2.3 microseconds. Nitrogen-14 is one of two stable (non-radioactive) isotopes of the chemical element nitrogen, which makes about 99.636% of natural nitrogen. Nitrogen-14 is one of the very few stable nuclides with both an odd number of protons and of neutrons (seven each) and is the only one to make up a majority of its element. Each of proton or neutron contributes a nuclear spin of plus or minus spin 1/2, giving