Crystal spectrometer for measurements of pionic X-rays

Abstract A description is given of a bent-crystal spectrometer for pionic X-rays. The instrument is of the modified DuMond type and makes use of a combined π-production-X-ray target. It is situated in a 20 μA, 590 MeV proton beam at SIN. Combination of high mechanical precision and a laser interferometer system makes it possible to measure wavelength ratios with a precision of 1–2 parts per million.