 Oliphant followed up the work by constructing a particle accelerator that could fire protons with up to 600 @,@ 000 electronvolts of energy . He soon confirmed the results of Cockroft and Walton on the artificial disintegration of the nucleus and positive ions . He produced a series of six papers over the following two years . In 1933 , the Cavendish Laboratory received a gift from the American physical chemist Gilbert N. Lewis of a few drops of heavy water . The accelerator was used to fire heavy hydrogen nuclei ( deuterons , which Rutherford called <unk> ) at various targets . Working with Rutherford and others , Oliphant thereby discovered the nuclei of Helium @-@ 3 ( helions ) and tritium ( tritons ) . 
