This experiment is part of our research programme to explore novel quantum phases and phase transitions induced by magnetic field in frustrated quantum magnets. The quasi-2D frustrated triangular quantum magnet Cs2CuBr4 shows a 1/3rd magnetization plateau in applied field. Plateau phases are very interesting as they represent particularly robust ground states and in this case the stability mechanism is proposed to be correlated quantum fluctuations which become particularly enhanced near the commensurate 1/3rd filling fraction and spontaneously open up a spin gap in the spectrum. This theoretical scenario has never been tested experimentally before as Cs2CuBr4 is the only example of a triangular quantum magnet with a plateau phase. We plan to measure the spin excitations in applied field to determine the origin and properties of this quantum fluctuations-stabilized plateau phase.