Ionising Radiation
Light, Sound and Waves

Villard’s deviable rays

Stories from Physics for 11-14 14-16 IOP RESOURCES

The discoverer of gamma rays, Paul Villard, received little credit for his work during his lifetime and his contribution was only fully recognised a century after his original research. Villard had used a Crookes tube to study cathode rays that were referred to as ‘deviable’ rays because they could be deflected by magnetic fields. He obtained a sample of radium from the Curies and discovered that the element also emitted deviable rays. However, he noted that his source also emitted a type of radiation that was not deflected by magnetic fields and reported the discovery in 1900. Perhaps because Villard did not label the rays and went on to research X-rays and cathode rays, his contribution has only recently been acknowledged. Rutherford later named the rays Villard had observed ‘gamma rays’, to join the alpha and beta radiations he had already identified.


Ionising Radiation
is used in analyses relating to Radioactive dating
can be analysed using the quantity Half-Life Decay Constant Activity
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