﻿304 Rise ofy-Ray Activity of Radium Emanation. 



Table 1. , 

 Absorbing medium is Lead, except where otherwise shown. 



Thickness of 

 Absorbing Plate. 



Value of jw (cm.— i) Moseley Rutherford 



for and and 



Radium-B rays. Makower. Richardson. 



160-200 mm 



2-7 cm.-l 



_ 



Varying from 



100-150 ,, 



2-8 cm -i 



.... 



11-0 cm.-l 



4-0- 6-0 „ 



4-1 cm.- 1 



4-0 cm.-l 



to 







(lead). 



2-8 cm.-l in 



1-5- 2-0 „ 



6-2 cm.-l 



6-0 cm.-l 



lead. 



3-0- 4-0 „ (Aluminium). 

 - 75 mm. (Aluminium) ... 



1-7 cm.-l (Al) 



10-0 cm.-l (Al) 



(lead). 

 ? 





Table II. 



Rise of Radium B from Radium Emanation. 



Maximum = 0*97480 is taken as unity. 



Time 

 in 

 mins. 

 1 



Calculated 

 rise of 



Radium B. 

 .. 0-00269 

 .. 0-01016 

 .. 002129 

 .. 003513 

 .. 005115 

 .. 0-06882 

 .. 0-08718 

 .. 010647 

 .. 0-12622 

 .. 0-14624 

 .. 0-16637 

 .. 0-18641 



Time 



in 

 mins. 



14.. .. 



16 



18 



20 



30 



Calculated 



rise of 

 Radium B. 

 ... 0-2260 

 ... 0-2649 

 ... 03023 

 ... 0-3379 

 . . . 0-4942 



Time 

 in 



mins. 

 110 



Calculated 



rise of 

 Radium B. 

 ... 0-9502 



2 



120 



1W 



.. 09643 



3 



... 0-9750 



4 



140 



150 



160 



170 



180 



190 



200 



210 



214 



220 



... 0-9835 

 ... 0-9886 



6 



7 



8 



40 



50 



<0 



70 



80 



90 ..... 

 100 



... 0-6135 

 ... 0-7066 



... 0-7780 

 .. 0-8329 

 ... 0-8748 

 ... 0-9058 

 ... 0-9315 



... 0-9929 

 ... 0-9956 

 ... 0-9979 



9 



10 



11 



12 



... 0-9992 

 ... 0-9998 

 ... 0-9999 

 ... 1-0000 

 ... 0-9999 



Summary. 



Curves showing the rise of 7-ray activity from pure 

 radium emanation measured through a wide range of 

 absorption thickness of matter have been determined and 

 utilized in deducing the absorption coefficients of the hetero- 

 geneous 7 radiation from radium B. 



My thanks are due to Professor Sir E. Rutherford for his 

 invaluable help in carrying out this research, and to 

 Mr. G. A. R. Crowe for the preparation of the radioactive 

 material. 



