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Computing the total disintegration energy given by the equation = (), where m i is the initial mass of the nucleus, m f is the mass of the nucleus after particle emission, and m p is the mass of the emitted (alpha-)particle, one finds that in certain cases it is positive and so alpha particle emission is possible, whereas other decay modes ...
Secondly, he found the charge-to-mass ratio of alpha particles to be half that of the hydrogen ion. Rutherford proposed three explanations: 1) an alpha particle is a hydrogen molecule (H 2) with a charge of 1 e; 2) an alpha particle is an atom of helium with a charge of 2 e; 3) an alpha particle is half a helium atom with a charge of 1 e.
An example of cosmic ray spallation is a neutron hitting a nitrogen-14 nucleus in the Earth's atmosphere, yielding a proton, an alpha particle, and a beryllium-10 nucleus, which eventually decays to boron-10. Alternatively, a proton can hit oxygen-16, yielding two protons, a neutron, and again an alpha particle and a beryllium-10 nucleus.
The alpha particle is an especially strongly bound nucleus, helping it win the competition more often. [57]: 872 However some nuclei break up or fission into larger particles and artificial nuclei decay with the emission of single protons, double protons, and other combinations. [55] Beta decay transforms a neutron into proton or vice versa.
11 C, carbon-11 is usually produced by cyclotron bombardment of 14 N with protons. The resulting nuclear reaction is 14 N(p,α) 11 C. [36] Additionally, carbon-11 can also be made using a cyclotron; boron in the form of boric oxide is reacted with protons in a (p,n) reaction. Another alternative route is to react 10 B with deuterons.
The range depends on the type of particle, on its initial energy and on the material through which it passes. For example, if the ionising particle passing through the material is a positive ion like an alpha particle or proton, it will collide with atomic electrons in the material via Coulombic interaction.
Protons and neutrons are, in turn, made of quarks. Each type of atom corresponds to a specific chemical element. To date, 118 elements have been discovered or created. Exotic atoms may be composed of particles in addition to or in place of protons, neutrons, and electrons, such as hyperons or muons. Examples include pionium (π − π +
Ernest Rutherford (1919) observed that nitrogen under alpha-particle bombardment ejects what appeared to be hydrogen nuclei. By 1920 he had accepted that the hydrogen nucleus is a distinct particle within the atom and named it proton. Neutrons have no electrical charge and have a mass of 1.6749 × 10 −27 kg.