Windowless position‐sensitive x‐ray detector for a Rowland circle crystal spectrometer

The output from an x‐ray detector using a Chevron pair of microchannel plates has been linearly encoded using an artificial delay line technique. The detector, operating in the wavelength region 12–30 A, has been mounted on the focusing plane of a Johann crystal spectrometer, radius 25 cm, and used to survey the spectrum from the Divertor Injection Tokamak Experiment (DITE) tokamak. The 20×20 mm2 detector is encoded by a remote, CAMAC based, computer acquisition system which at an electronic count rate of 1×105 Hz shows negligible degradation of the spectral profiles. Events encoded along the 20‐mm dimension are directly histogrammed into a CAMAC memory which is capable of recording 128 time frames each with 256 spectral bins with 12 bits/bin. In nonoptimized tests, a FWHM of 60 μm is observed, and a count rate up to 2×104 Hz/mm has been achieved. The high‐resolution capability and the shallow detection depth of the microchannel plate both complement the low f number of the spectrometer. Results are repor...