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
British nuclear tests at Maralinga nuclear warheads containing plutonium-239. In total, "Vixen B" scattered 22.2 kg of plutonium around the Maralinga test site known as Taranaki, in particles of widely divergent size. Plutonium is not particularly dangerous externally - it emits alpha particles which are stopped by of air, or the dead layer of skin cells on the body, and is not a very intensive source of radiation, due to its long half-life of 24,000 years. It is most dangerous when it enters the body, in the worst case by breathing, and therefore tiny particles, often the result of such explosion testing, are the worst