Mounting powder samples for sub-Kelvin neutron diffraction

The increasing availability of ³He-based cryostats is making it possible to add sub-Kelvin capabilities to powder diffraction instruments. However, there are many problems associated with cooling powders below 1 K, and if great care is not taken, the sample temperature may be far higher than that reported by a thermometer attached to the sample holder. This contribution describes two practical and effective strategies for mounting powder samples that yield equilibration times of at most a few tens of minutes.