  A single terbium foil was irradiated with 800 MeV protons to ascertain the
potential for production of lanthanide isotopes of interest in medical,
astrophysical, and basic science research and to contribute to nuclear data
repositories. Isotopes produced in the foil were quantified by gamma
spectroscopy. Cross sections for 36 isotopes produced in the irradiation are
reported and compared with predictions by the MCNP6 transport code using the
CEM03.03, Bertini, and INCL+ABLA event generators. Our results indicate the
need to accurately consider fission and fragmentation of relatively light
target nuclei like terbium in the modeling of nuclear reactions at 800 MeV. The
predictive power of the code was found to be different for each event generator
tested but was satisfactory for most of the product yields in the mass region
where spallation reactions dominate. However, none of the event generators'
results are in complete agreement with measured data.
