XFR analyzer instrument

An X-ray fluorescence (XRF) analyzer instrument for analysis of elemental composition of a sample, the XRF analyzer instrument comprising:

• a hermetically sealed measurement chamber comprising air and provided with a measurement aperture that is sealed by a sample window;
• a radiation source having its radiation-emitting portion disposed inside the measurement chamber and arranged to emit primary radiation towards the sample window so as to invoke secondary radiation from the sample arranged adjacent to the sample window on an exterior of the measurement chamber;
• a radiation detector having its radiation-receiving portion disposed inside the measurement chamber, the radiation detector arranged to receive the secondary radiation from a direction of the sample window and to provide a measurement signal that is descriptive of intensity of the received radiation;
• a controller arranged to carry out the analysis of elemental composition of the sample on the basis of an energy spectrum of the measurement signal in accordance with a calibration established at a reference air density inside the measurement chamber;
• and
• a volume adjustment assembly arranged to adjust a volume of the measurement chamber for restoring the reference air density inside the measurement chamber after a change in air density inside the measurement chamber in order to maintain validity of said calibration.