(C5H12N)2CuBr4 is the best realisation found to date of an antiferromagnetic quantum spin ladder in the strong coupling limit. This system displays an extremely rich phase diagram as a function of applied magnetic field, with two quantum critical points, and six distinct phases including a spin Luttinger liquid, and a Bose-Einstein condensate (BEC) of magnons. While many of its salient features have been elucidated in a series of experiments, important questions still remain to be addressed. Here we are applying for beam time to exploit the exceptional capabilities of LET to measure the magnetic excitations of the model spin ladder (C5H12N)2CuBr4. This will allow us to determine for the first time the mechanism of thermally induced triplet formation and the excitations in the high-energy sector above the first quantum critical point.