Chronology of Milestone Events in Particle Physics - VILLARD 1900
Chronology of Milestone Events in Particle Physics

VILLARD 1900

Villard, P.;
Sur la Réflexion et la Réfraction des Rayons Cathodiques et des Rayons Déviables du Radium / On the Reflection and Refraction of Cathode Rays and Deviable Rays of Radium
Compt. Ren. 130 (1900) 1010;

Reprinted in
(translation into English, excerpt) The World of the Atom, editors H. A. Boorse and L. Motz, Basic Books, New York - London, V.I (1966) 447.

Motivation
The deviable rays from radium behave like the cathode rays in Crookes tubes; the experiment was made in the following manner.
A small Quantity of radium-bearing barium chloride enclosed in a thin glass ampoule was placed in a lead tube, one of the ends of which, completely open, allowed a cone of rays of about 20 degrees spread to emerge. At 2 or 3 mm in front of this opening there was fixed a small aluminium plate, 0.3 mm thick, inclined at 45 degrees to the axis of the tube and placed in such a way as to intercept half the beam. All of this was placed on a photographic plate wrapped in a double sheet of black paper which received the emerging beam at almost grazing incidence. The impression produced on the photographic plate showed that the half-beam which had struck aluminium, instead of continuing its path in a straight line and remaining symmetrical with the non-intercept half beam, followed a direction clearly normal to the aluminium sheet. This refraction is accompanied by a strong scattering. Except for the greater thickness of metal traversed, the phenomenon is the same as in Crookes tubes.

Accelerator SOURCE Detectors EMUL

Related references
See also
M. Curie, Compt. Ren. CXXX (1900) 73;

Reactions
  Ra* Ra γ

Particles studied
  γ ex, qn

Record comments
Evidence for the γ radioactivity.
    
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