An x-ray analyser for a transmission electron microscope is described. The analyser has a silicon drift detector moveable in use between an analysis position and a retracted position. The analyser has a housing having an end portion within which the silicon drift detector is retained. The end portion is formed from a material with a relative magnetic permeability of less than 1.004. The analyser also has an automatic retraction system adapted to move the silicon drift detector from the analysis position to the retracted position upon receipt of a trigger signal indicative of a condition in which the power level received by the silicon drift detector from impinging x-rays or electrons is above a predetermined threshold.
