Abstract: X-rays can be used for material identification. X-ray beam purity, target adhesion the x-ray window, and a robust hermetic seal of the x-ray window are useful. To achieve these objectives, a target 17 can be mounted by an adhesion-layer 16 on the x-ray window. The adhesion-layer 16 can include chromium. A sealing-layer 13 can seal the x-ray window to a flange 19. Material of the sealing-layer 13 can be different from material of the adhesion-layer 16. There can be a gap 21 between the flange 19 and the target 17. There can be a conductive-layer 18 on the x-ray window 14 in the gap 21. A thickness Ts of the adhesion-layer 16 between the sealing-layer 13 and the x-ray window 14 can be different than a thickness Tt of the adhesion-layer 16 between the target 17 and the x-ray window 14.