64 



ADVENTURES IN RADIOISOTOPE RESEARCH 



activity was obtained we can conclude that hafnium does not belong 

 to the elements showing a strong artificial radioactivity. This is partly 

 due to the fact that the capture of neutrons by most of the hafnium 

 isotopes leads, as explained later, to the formation of a heavier stable 



200 days 



F"ig. 1. Decay Curve of Hafnium. 



isotope ; as stable isotopes 176, 177, 178, 179, and 180 are known and 

 only the absorption of neutrons by the last mentioned isotope can lead 

 to the formation of an active product. The relative abundance of the 

 isotopes in the naturally occurring element hafnium, as determined 

 by Aston, is seen from Table 2. 



Table 2. — Relative Abvxdance of the Hafnium Isotopes 



