Editing Beta particle (section)

== History ==
[[Henri Becquerel]], while experimenting with [[fluorescence]], accidentally found out that [[uranium]] exposed a [[photographic]] plate, wrapped with black paper, with some unknown [[radiation]] that could not be turned off like [[X-ray]]s.

[[Ernest Rutherford]] continued these experiments and discovered two different kinds of radiation:

* [[alpha particles]] that did not show up on the Becquerel plates because they were easily absorbed by the black wrapping paper
* beta particles which are 100 times more penetrating than alpha particles.

He published his results in 1899.<ref>{{cite journal |author=E. Rutherford |url=https://books.google.com/books?id=ipMOAAAAIAAJ&pg=PA109 |title=Uranium radiation and the electrical conduction produced by it |journal=Philosophical Magazine |volume=47 |issue=284 |pages=109–163 |doi=10.1080/14786449908621245 |date=8 May 2009 |orig-year=Paper published by Rutherford in 1899}}</ref>

In 1900, Becquerel measured the [[mass-to-charge ratio]] ({{math|''m''/''e''}}) for beta particles by the method of [[J. J. Thomson]] used to study cathode rays and identify the electron. He found that {{math|''e''/''m''}} for a beta particle is the same as for Thomson's electron, and therefore suggested that the beta particle is in fact an electron.