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.
Ariel Atom 3.8 seconds. At the National Exhibition Centre in Birmingham, the Atom broke the indoor speed record. The high gloss floor that the cars ran on was only long, with an open door at the end of the hall. The driver of the Atom launched in fourth gear and still had wheelspin until the car reached and started to get traction. The Atom was beaten only by a class nine Autograss car powered by a 2.0l Lexus-Toyota touring car engine which set the official indoor speed record, beating the previous record held by a Toyota F1 car driven by "Top Gear"'s