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Mr Kaye, The Emission of Rontgen Hays 



the distribution of the Rontgen rays produced by the impact of 

 cathode rays on a thin metal target invited attack. The simplest 

 experimental conditions would be realised by the use of as thin 

 a metal anticathode as can be obtained, and by employing cathode 

 rays of uniform velocity. This latter condition is being satisfied 

 in experiments now in progress, but as the cathode rays in soft 

 coil-driven Rontgen ray tubes are not very heterogeneous it seemed 

 worth while to carry out preliminary experiments in which the 

 condition of homogeneity of the cathode rays was waived. More- 

 over it has to be remembered that the Rontgen rays emitted will 

 be diluted to some extent with secondary Rontgen rays produced 

 by the action of the primary X ray beam on the material of the 

 anticathode. It remained to see what effect this would have on 

 the distribution of the primary rays. 



Cathode 



Apparatus. 



The apparatus is sufficiently indicated by the figure. An 

 anticathode of thin metal leaf was mounted centrally in the 

 tube BJE, so that it could receive a pencil of cathode rays from 

 either side at an angle not far removed from the normal. The 

 X rays produced could pass out normally by the aluminium windows 

 D and E which, needless to say, were equally thick ('Ol cm.). 

 The idea in providing two cathodes G and C was to guard against 

 any possible want of symmetry in the apparatus. Plane cathodes 

 had to be employed ; such thin leaves as were used for anti- 

 cathodes puncture at once if any attempt is made to focus the 

 cathode rays. The tube was coil-driven. 



