686 



TABLE 747.— GAMMA-RAY ENERGY OF SOME HEAVY ISOTOPES, NATURAL 



AND ARTIFICIAL 



These differences of energies, or velocities, of the a-ray from thorium C are sometimes 

 explained on the energy-level basis of the nucleus. The agreement with the energies of 

 the 7-rays emitted from ThC", the daughter of ThC, and these apparent differences of 

 disintegration energy of a-ray of ThC, given in the table show one agreement with this 

 theory. 



* For reference, see footnote 225, p. 666. 



TABLE 749.— DANGER RANGES FOR PERSONS WHO ARE WORKING WITH 

 RADIUM, FOR DIFFERENT AMOUNTS OF RADIUM, PROVIDING 

 THE RADIUM IS ENCLOSED IN NOT LESS THAN 1 mm LEAD 

 OR ITS EQUIVALENT 



Amount of radium 

 element milligrams 



100 



200 



400 



1000 



Daily exposure (in hours) 



SMITHSONIAN PHYSICAL TABLES 



