The Detection of Light Elements

Abstract

The microanalyser built at the R.A.R.D.E uses a modified Duncumb lens with six re-entrant ports. Geometric and spatial restrictions make it difficult to design a fully-focussing spectrometer of high efficiency for use with a lens of this type. Focussing spectrometers of limited range have been constructed [1] and a multi-crystal instrument is being built using focussing geometry on the specimen side only. This spectrometer however, like the semi-focussing instrument it will replace, requires a counter with a large window in order to intercept the whole of the diffracted beam at the higher values of θ, and the difficulty of making thin windows of sufficient strength increases with their physical size.