Determination of neutron fluence based on the measurement of isotopic variation of cadmium and gadolinium

The determination of neutron fluence using mass spectrometric measurements of the isotopic composition variation of elements with high neutron capture cross section has been attempted. Cadmium and gadolinium have been used as monitors. The results indicate that the fluence values obtained using the variation in the isotopic ratio 114Cd/113Cd present a standard deviation of the order of 15%, whereas values calculated using 158Gd/157Gd show a deviation of about 5%. The fluence values calculated by the two methods agree within about 10%. (orig.)