Atom 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 free mass of 1,839 times the mass of the electron, or , the heaviest of the three constituent particles, but it can be reduced by the nuclear binding energy. Neutrons and protons (collectively known as nucleons) have comparable dimensions—on the order of —although the 'surface' of these particles is not sharply defined. The neutron was discovered in 1932 by the English physicist James Chadwick.
Captain Atom which returns Captain Atom to his usual self (if somewhat confused). In 2005/2006, Captain Atom appears in a nine-part limited series entitled "Captain Atom: Armageddon" under DC's Wildstorm imprint. Captain Atom's sacrifice in "Superman/Batman" sends him to the WildStorm universe for the duration of the series. In this title, he wears a yellow/red outfit that was first seen in the 1996 "Kingdom Come" limited series. At the moment of his apparent death, Captain Atom experiences a time-shift coinciding with his 2005 appearance in "Superman/Batman", resulting in his arrival in the Wildstorm Universe. He quickly gets into a fight with an