  The article by Fernandez et al argues that, because of advances made in
laser-produced neutron pulses, it should now be possible to measure temperature
in samples loaded to elevated pressures, by neutron resonance spectrometry with
neutrons accelerated using a single sub-picosecond laser pulse in the 300J
range. We point out that the configuration used for neutron source and detector
would require an infeasibly large sample, potentially requiring tens of
megajoules of laser energy to drive the sample. The laser-driven neutron
technology is thus not yet mature enough to consider for new facilities, and
the previously-demonstrated experiments at LANSCE still represent the only
credible point design. We summarize some possible strategies for coupling
brighter neutron sources with dynamic loads.
