  The results of measurements of the production of neutron-rich nuclei by the
fragmentation of a 48Ca beam at 142 MeV/u are presented. Evidence was found for
the production of a new isotope that is the most neutron-rich silicon nuclide,
44Si, in a net neutron pick-up process. A simple systematic framework was found
to describe the production cross sections based on thermal evaporation from
excited prefragments that allows extrapolation to other weak reaction products.
