Comment on J. Fernandez et al, "Requirements and sensitivity analysis for temporally- and spatially-resolved thermometry using neutron resonance spectroscopy," Rev. Sci. Instrum. 90, 094901 (2019)

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.