72 



ISOTOPIC TRACERS AND NUCLEAR RADIATIONS 



[Chap. 3 



Table 7. Ranges and Absorption Coefficients of Beta Particles from Radio- 

 active Isotopes 

 The data listed below are a compilation of values reported in recent literature. In 

 order to avoid confusion in using the table, reference numbers for each value have been 

 omitted but the principal literature from which data were obtained is listed at the end of 

 the table. The maximum range, in mg/cm 2 , is given when known for aluminum and 

 water as indicated by Al or W following its value. In most cases the range was deter- 

 mined by Feather's method. The absorption coefficient a is defined by the usual expres- 

 sion / = I e~ at where t is the thickness of aluminum absorber in milligrams per square 

 centimeter. Values reported in the literature for the same isotope sometimes differ con- 

 siderably in magnitude, but no effort was made to rectify these differences. 



