Key points are not available for this paper at this time.
A method of determining the ratio of two small currents which vary intermittently or continuously, but always have the same relative magnitudes, is described. Although applied only to the case of making precise measurement of ratio of two ion currents in a mass spectrometer for the purpose of measuring the relative abundance of isotopes, the method would be useful in other applications as well.
Nier et al. (Thu,) studied this question.