[Letter from Howard E. Smither]

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“…Although the sensitivity is low, it is sufficient to study partial cross sections above 0.1 barn. The two most widely used installations are located at Argonne (264)(265)(266)(267)(268)(269)(270)(271) and at Risp , the latter being operated by the Technische Hochschule Munchen. The Ris¢ spectrometer, often operated at high energies in the fifth order of reflection, has allowed observations with a resolution of 17 eV at 90 k eY and 0.43 keY at 900 keY.…”