“…The construction of a device to access this "ultra"-low temperature spinning (ULTMAS) regime is far from straightforward and specific limitations as cost and loss of (precious) He or low kinematic viscosity of He gas inhibiting stable MAS [25]. However, the benefits are numerous, embracing an increased Boltzmann distribution (cf., ~0.1% 1H polarization at 10 K, ~0.003% at 300 K, all at 10 T), reduced Johnson-Nysquist noise in the radio frequency (RF) circuit, in addition of being able to study low-temperature phenomena at an atomic scale [22,26]. Hardware for ULT-MAS combined with DNP at temperatures <<100 K, has been developed in the teams of R. Griffin at the Massachusetts Institute of Technology (MIT), USA [12], R. Tycko in Bethesda (NIH), USA [14], and T. Fujiwara in Osaka, Japan [16].…”