689 



TABLE 752.— GAMMA SPECTRUM FOR SOME RADIOACTIVE BREAKDOWNS 



(concluded) 



238 San Tsiang Tsien, Phys. Rev., vol. 69, p. 38, 1946. 



TABLE 753.— THE ENERGY RADIATED BY A NUMBER OF RADIOACTIVE 



MATERIALS* 



Material 

 92 Uranium 238 



(Uranium I) 

 90 Thorium 232 

 88 Radium 226 

 86 Radon 222 

 86 Radon 220 



(Thoron) 

 86 Radon 219 



(Actinon) 

 86 Radon 217 

 84 Polonium 214 



(Radium C) 

 84 Polonium 212 



(Thorium C) 

 84 Polonium 211 



(Actinium C) 

 84 Polonium 210 

 83 Bismuth 214 

 81 Thallium 210^ 



(Radium C") 

 81 Thallium 208 



(Thorium C") 

 81 Thallium 207 



(Actinium C") 

 59 Praseodymium 142 

 53 Iodine 136 

 19 Potassium 40** 



* For reference, see footnote 199, p. 618. 



** The radiation from potassium may seem to be too intense as compared to that from thorium 232 or 

 uranium 238 but it must be remembered that the active isotope of potassium constitutes only .01 percent of 

 ordinary potassium while the active isotopes of uranium and thorium constitute about 100 percent of the mate- 

 rial. It is also to be noted that the active isotope of potassium has more disintegration than either uranium or 

 thorium, in part due to its greater number of atoms per gram. 



TABLE 754.— SAFE WORKING DISTANCES FOR DIFFERENT EXPOSURE 

 TIMES TO DIFFERENT AMOUNTS OF RADIUM 



SMITHSONIAN PHYSICAL TABLES 



