Alpha particle types: eventually named alpha, beta, and gamma by Rutherford, based on penetration of objects and deflection by a magnetic field. Alpha rays were defined by Rutherford as those having the lowest penetration of ordinary objects. Rutherford's work also included measurements of the ratio of an alpha particle's mass to its charge, which led him to the hypothesis that alpha particles were doubly charged helium ions (later shown to be bare helium nuclei). In 1907, Ernest Rutherford and Thomas Royds finally proved that alpha particles were indeed helium ions. To do this they allowed alpha particles to penetrate a very thin
Dubnium by bombarding californium-249 with nitrogen-15 ions, with an alpha activity of 9.1 MeV. To ensure this activity was not from a different reaction, the team attempted other reactions: bombarding Cf with N, Pb with N, and Hg with N. They stated no such activity was found in those reactions. The characteristics of the daughter nuclei matched those of 103, implying that the parent nuclei were of 105. These results did not confirm the JINR findings regarding the 9.4 MeV or 9.7 MeV alpha decay of 105, leaving only 105 as a possibly produced isotope. JINR then attempted another experiment to