Abstract : The neutron yield of thick targets of carbon, natural and enriched in 13C, bombarded by
deuterons of 20 and 30 MeV has been measured by the activation method. The gain with respect to a 12C
target is the same as with protons beams. The yield ratio is about 1.2 only and hardly can justify the use
of a 13C target with deuteron beams. The data, apart from being of interest for the design of facilities
where secondary neutron beams are used, provide a test case for calculations where both beam and target
have a weakly-bound neutron. The MCNPx code version 2.6.0, despite failing to reproduce some details
of the experimental distributions, describes their global properties fairly well, especially the relative yields
of the 12C and 13C targets.
