Roentgen (unit) capped at 3 MeV in 1950. The USSR all-union committee of standards (GOST) had meanwhile adopted a significantly different definition of the roentgen in 1934. GOST standard 7623 defined it as "the physical dose of X-rays which produces charges each of one electrostatic unit in magnitude per cm of irradiated volume in air at 0 °C and normal atmospheric pressure when ionization is complete." The distinction of physical dose from dose caused confusion, some of which may have led Cantrill and Parker report that the roentgen had become shorthand for 83 ergs per gram (0.0083 Gy) of tissue. They named
Discovery of the neutron elements by neutron irradiation (1934) and the fission of uranium atoms by neutrons (1938). The discovery of fission led to the creation of both nuclear power and weapons by the end of World War II. Both the proton and neutron were presumed to be elementary particles until the 1960s when they were determined to be composite particles built from quarks. At the start of the 20th century, the vigorous debate as to the existence of atoms had not yet been resolved. Philosophers such as Ernst Mach and Wilhelm Ostwald denied that atoms were real, viewing them as a convenient mathematical