Who was the scientist that generated Hydrogen nuclei from reactions between nitrogen gas and alpha particles ?
In 1932 , Chadwick exposed various elements , such as hydrogen and nitrogen , to the mysterious " beryllium radiation " , and by measuring the energies of the recoiling charged particles , he deduced that the radiation was actually composed of electrically neutral particles which could not be massless like the gamma ray , but instead were required to have a mass similar to that of a proton .