  Characterizing plasticity mechanisms below the ductile-to-brittle transition
temperature is traditionally difficult to accomplish in asystematic fashion.
Here, we use a new experimental setup to perform in situ cryogenic mechanical
testing of pure Sn micropillars at room temperature and at 142{\deg}C.
Subsequent electron microscopy characterization of the micropillars shows a
clear difference in the deformation mechanisms at room temperature and at
cryogenic temperatures. At room temperature, the Sn micropillars deformed
through dislocation plasticity, while at142{\deg}C they exhibited both higher
strength and deformation twinning. Two different orientations were tested, a
symmetric (100) orientation and a non-symmetric (451) orientation. The
deformation mechanisms were found to be the same for both orientations
