Pc1 measurements of EMIC waves are not significantly linked to the acceleration of auroral protons in the cusp.

We present three pieces of observational evidence to conclude that EMIC waves are not the mechanism responsible for the acceleration of auroral protons in the polar cusp. It is widely believed that ElectroMagnetic Ion Cyclotron (EMIC) plasma waves are the mechanism responsible for the acceleration of auroral protons - however, measurements of auroral proton precipitation and Pc1 pulsations from Svalbard under the cusp region indicate that there is no significant link between the two phenomena. Spectrograph measurements of proton aurora over Svalbard are studied alongside co-located magnetometer measurements of Pc1 pulsations. No evidence of a link between proton aurora and Pc1 waves was found by three different methods. Firstly, accelerated protons and Pc1 pulsations have no coincident occurrence. Secondly, the proton energy spectrum does not change between Pc1 activity and quiet times. Finally, no imprint of the EMIC wave is found in periodicity of the intensity and blue-shift of the proton H-$\alpha$ line, unlike in flickering electron aurora where intensity fluctuations are caused by EMIC waves. It may be possible that EMIC waves are causing acceleration but not propagating down to cause Pc1 pulsations, however we deem this unlikely. Therefore we conclude that EMIC waves are not the mechanism responsible for accelerating auroral protons in the cusp.