A Dempster-type double-focussing mass spectrometer has been used to determine the relative abundances of the isotopes of neodymium using two samples, one irradiated in a strong neutron flux, the other, obtained from the same source, unirradiated. A comparison of these results permits the calculation of the cross-section of each isotope for the capture of pile neutrons. Results previously obtained have been extended to give definite cross-sections for three of the isotopes, two of which have not previously been reported, and to lower the upper limits for the remainder. / Thesis / Master of Science (MS)