Abstract: The measurement head (101) of an X-ray fluorescence analyzer device is protected against heat from a hot target by using an adapter (201). It comprises a sheet of material having low thermal conductivity and has a three-dimensional shape that follows the form of a front part of the measurement head (101). Said sheet of material is attached to said measurement head (101) and has a central part (401) which defines an opening (202) coincident with a radiation window (109) in said measurement head (101). Said attachment means (204, 205, 301, 302, 311, 312) are located at a part of said sheet of material that is distant from said central part (401).