Metal ions in aqueous solution radial distribution function. In contrast to X-ray diffraction, neutrons are scatted by nuclei and there is no relationship with atomic number. Indeed, use can be made of the fact that different isotopes of the same element can have widely different scattering powers. In a classic experiment, measurements were made on four nickel chloride solutions using the combinations of Ni, Ni, Cl and Cl isotopes to yield a very detailed picture of cation and anion solvation. Data for a number of metal salts show some dependence on the salt concentration. Most of these data refer to concentrated solutions in which there
Neutron 1942) and the first nuclear weapon (Trinity, 1945). Free neutrons, while not directly ionizing atoms, cause ionizing radiation. As such they can be a biological hazard, depending upon dose. A small natural "neutron background" flux of free neutrons exists on Earth, caused by cosmic ray showers, and by the natural radioactivity of spontaneously fissionable elements in the Earth's crust. Dedicated neutron sources like neutron generators, research reactors and spallation sources produce free neutrons for use in irradiation and in neutron scattering experiments. Atomic nuclei are formed by a number of protons, Z the atomic number, and a number of neutrons,