<P> Due to the short range of absorption and inability to penetrate the outer layers of skin, alpha particles are not, in general, dangerous to life unless the source is ingested or inhaled . Because of this high mass and strong absorption, if alpha - emitting radionuclides do enter the body (upon being inhaled, ingested, or injected, as with the use of Thorotrast for high - quality X-ray images prior to the 1950s), alpha radiation is the most destructive form of ionizing radiation . It is the most strongly ionizing, and with large enough doses can cause any or all of the symptoms of radiation poisoning . It is estimated that chromosome damage from alpha particles is anywhere from 10 to 1000 times greater than that caused by an equivalent amount of gamma or beta radiation, with the average being set at 20 times . A study of European nuclear workers exposed internally to alpha radiation from plutonium and uranium found that when relative biological effectiveness is considered to be 20, the carcinogenic potential (in terms of lung cancer) of alpha radiation appears to be consistent with that reported for doses of external gamma radiation i.e. a given dose of alpha - particles inhaled presents the same risk as a 20 - times higher dose of gamma radiation . The powerful alpha emitter polonium - 210 (a milligram of Po emits as many alpha particles per second as 4.215 grams of Ra) is suspected of playing a role in lung cancer and bladder cancer related to tobacco smoking . Po was used to kill Russian dissident and ex-FSB officer Alexander V. Litvinenko in 2006 . </P> <P> In the years 1899 and 1900, physicists Ernest Rutherford (working in McGill University in Montreal, Canada) and Paul Villard (working in Paris) separated radiation into three 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 . </P> <P> 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 glass wall of an evacuated tube, thus capturing a large number of the hypothesized helium ions inside the tube . They then caused an electric spark inside the tube, which provided a shower of electrons that were taken up by the ions to form neutral atoms of a gas . Subsequent study of the spectra of the resulting gas showed that it was helium and that the alpha particles were indeed the hypothesized helium ions . </P> <P> Because alpha particles occur naturally, but can have energy high enough to participate in a nuclear reaction, study of them led to much early knowledge of nuclear physics . Rutherford used alpha particles emitted by radium bromide to infer that J.J. Thomson's Plum pudding model of the atom was fundamentally flawed . In Rutherford's gold foil experiment conducted by his students Hans Geiger and Ernest Marsden, a narrow beam of alpha particles was established, passing through very thin (a few hundred atoms thick) gold foil . The alpha particles were detected by a zinc sulfide screen, which emits a flash of light upon an alpha particle collision . Rutherford hypothesized that, assuming the "plum pudding" model of the atom was correct, the positively charged alpha particles would be only slightly deflected, if at all, by the dispersed positive charge predicted . </P>

What would happen if a nucleus emitted three alpha particles