432 Mr. H. F. Biggs on Energy of Secondary Beta Rays 



Incidentally, the results confirm Rutherford's theory that 

 the observed great energy of the faster j3 particles is derived 

 Prom the known 7 rays, each /3 particle carrying several of 

 their energy quanta, and is not due to a hypothetical y radia- 

 tion of such high frequency that only one quantum of energy 

 is required. 



Apparatus. 



The source, S (fig. 1), of 7 rays was 64 mg. of RaBr 2 with 

 its products in a steady state. The radium was contained 



Fio-. 1. 









Ap 



I 



\ 



'A 



\ 



|| 





10 cm. 



in a platinum tube enclosed in a sealed glass tube. The glass 

 tube was fixed to a lead plate so that it could be removed 

 (for safe keeping) and exactly replaced. Pb is a lead block 

 so placed that the shortest line from any radium to the 

 nearest point of the electroscope lay through about 20 cm. of 

 lead. The electroscope, E, 10 cm. cube, was of block tin 

 with a lead casing 3 mm. thick. One side was closed only 

 by aluminium foil. Opposite this side could be hung on a 

 light frame the radiator, R, a piece of lead foil 10 cm. square 



