VILLARD, P. (PAUL ULRICH). - THE DISCOVERY OF GAMMA RAYS AND GAMMA RADIATION.

Sur la réflexion et la réfraction des rayons cathodiques et des rayons déviables du radium. (+) Sur le rayonnement du radium.

(Paris, Gauthier-Villars, 1900). 4to. No wrappers. In: "Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences", Tome 130, No 15 a. No 18. Pp. (962-) 1044 a. pp. (1145-) 1220. Entire issues offered. Stamp on first pages. A few tears to margins. Poor paperquality, fragile. Villard's papers: pp. 1010-1012 a. 1178-1182, textillustrations.

First apperance of Villard's two papers in which he announced and described the discovery of a new type of radiation more powerfull and penetrating than alpha-and beta rays. The new type of rays was named by Rutherford as gammarays.

"His (Villard)experiments in radioactivity led to the unexpected discovery of gamma rays in 1900. Villard recognized them as being different from x rays because the gamma rays had a much greater penetrating depth. He had discovered they were emitted from radioactive substances and were not affected by electric or magnetic fields. These came to be called gamma rays by another scientist, Ernest Rutherford. It wasn't until 1914 that Rutherford showed that they were a form of electromagnetic (EM) like light only with a much shorter wavelength than x rays. Now we know that gamma rays are a form of EM radiation similar to x rays. Gamma rays tend to have a higher energy and a shorter wavelength than x rays do. However, the dividing line between these two forms of radiation is not clearly defined. Scientists typically apply the term gamma ray to EM radiation with energies above several hundred thousand electron volts." (Hps - Healt Physics Society). - See Sigmund Brandt "The Harevst of a Century", Episode 6, p. 24 ff.).

The issues contains other importent papers HENRI BECQUEREL "Note sur la transmission du rayonnement du radium au travers des corps", pp. 979-984 and "Sur la transparance de l'aluminium pour le rayonnement du radium", pp. 1154-57. P. CURIE et G. SAGNAC "Électrisation négative des rayons secondaires produits au moyen des rayons de Röntgen", pp. 1013-1016.

Order-nr.: 48207