70 



ISOTOPIC TRACERS AND NUCLEAR RADIATIONS 



[Chap. 3 



Table 6. Average Energy of Beta Particles 



The data given below are taken from the computed and compiled values of average beta energies 



reported by Marinelli, Brinckerhoff, and Hine, Rev. Mod. Phys., 19, 25 (1947). To ensure the highest 



accuracy they computed average values only from magnetic spectrometer measurements reported after 



1939. In the case of complex spectra, the average value of the components, determined from graphical 



analysis, is given as well as the average for the total spectrum. The average for simple spectra was 



computed from Fermi's theory for the energy distribution by the formula 



'Eo / [Eo 



E= I EN dE I I N dE (see Beta Decay, Sec. 3.11) 



fEo / fEi 



-/, ENdE / h 



The column giving percentage indicates either the per cent of beta particles with different E or the 

 per cent of positrons to K capture. In the case of positron emission the average total energy is indi- 

 cated by the product of the particle average energy and emission probability per disintegration printed 

 in parentheses. 



The asterisk * indicates that the values given refer only to the highest energy component of the 

 spectrum whereas the dagger t indicates the lowest energy component. 



