14 which is preferably a multi layer crystal the fluorescent x ray flux 26 is incident to the rotatable crystal 14 at an incidence angle 28 generally denoted as u03b8 the fluorescent x ray flux undergoes bragg diffraction by interaction with the rotatable crystal 14 resulting in a diffracted x ray flux 30 which is detected by an x ray detector 18 in the preferred embodiment the x ray detector 18 is a pin diode detector and is operated in pulse mode while performing wds measurements the x ray detector 18 is moved along an arc 22 by a goniometer not shown the motion of the x ray detector 18 is coupled to the rotation of the rotatable crystal 14 about axis of rotation 16 so that x ray detector 18 moves through a change along angle 32 of 2 u03b4 u03b8 for every u03b4 u03b8 change in incidence angle 28 angle 32 is the angle between the original path line 34 of the fluorescent x ray flux 26 and the path line 31 of the bragg diffracted x ray flux 30 the x ray detector 18 is movable between first and second endpoints 19 and 20 for purposes of making wds measurements at second endpoint 20 the x ray detector 18 is collinear with the original path line 34 of the fluorescent x ray flux 26 and will thus be in position for performing eds measurements in the preferred embodiment the range of movement of the x ray detector 18 along arc 22 is limited to about 50.