  Spacecraft observations in the inner heliosphere offer the first opportunity
to measure 1-10 MeV solar neutrons. We discuss the physics of low-energy
neutron production in solar flares and show that, even at interacting-particle
energies of 2 MeV/nucleon, neutrons with energies >10 MeV are produced. On the
other hand, a significant fraction of 1-10 MeV neutrons result from
interactions of >10 MeV/nucleon ions in typical flare spectra. We calculate the
escaping neutron spectra for mono-energetic and power-law particle spectra at
the Sun for the location and observation angle of MESSENGER at the time of its
reported detection of low-energy neutrons associated with the 2007 December 31
solar flare. We detail concerns about this questionable observation of solar
neutrons: 1. the inferred number of accelerated protons at the Sun for this
modest M2-class flare was 10X larger than any flare observed to date, 2. the
onset and duration of the 'solar' neutron count rate was similar to that of the
solar energetic particles (SEPs), and 3. the authors' argument that the SEPs
were dominated by electrons and so could not have produced the neutron counts
locally in the spacecraft. In contrast we argue that solar energetic protons
and alpha particles, through local neutron production and accidental
coincidences, were the source of most of the reported 'solar-neutron' counts.
