A Two‐Crystal Spectrometer for X‐Rays of Wave‐Length 0.030

A two‐crystal x‐ray spectrometer for use in the wave‐length region 0.030<λ<0.215A is described. Transmission and reflection of the x‐rays through the body of the crystal, instead of the usual reflection from the surface, is employed. An ionization chamber containing argon at 80 atmospheres, and an FP‐54 electrometer tube system is used to measure the intensity of the reflected radiation. A source of short wave‐length x‐rays, consisting of two specially designed induction coils and a cascade Coolidge tube, is described. Rocking curves in the (1, −1) position at 50 X.U., the K limits of lead and of uranium, and the Kα and Kβ‐lines of tungsten were observed for the purpose of calibrating the spectrometer. The resolving power of the instrument with the present crystals is discussed.