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



plotted against the thickness (in millimetres) o£ aluminium 

 through which the secondary rays have passed. The screen 

 Ay over the source is, in this case, '76 cm. of aluminium. 

 Curve R is for the radiator in place, curve X for the radiator 

 removed. 



Fig. 3 gives (in curve ii.) the result of subtracting curve X 

 from curve R in fig. 2, using the smoothed curves, with the 



Fig-. 3. 



20 



.1 









15 













JO 



\ !i mV\\ 













\ \- 















\Vv° Logl 













\\^Dlogll 













\^Ologlll 









\ 





\^ \}loglV 







5 



\Pb 



^ 



Vx 







I 







^^0\b Log Pb 







'5 mm. AL 



1-0 



1-5 



2-0 



other curves of the same type; that is, curves i.,ii., iii., iv., Pb, 

 are absorption curves in aluminium for the secondary radiation 

 due to primary radiation that has passed through 0, *76, 1*52, 

 2'2$ cm. of aluminium, and 1*71 cm. of lead respectively, 



