A PRECISION IRON-FREE π√2 BETA-RAY SPECTROMETER OF 35-CM OPTIC CIRCLE RADIUS

Abstract

An air-core high-resolving-power, high-luminosity double-focusing spectrometer of the high-aperture type is described. Focusing up to the fourth order in the axial departure angle is achieved with the use of three pairs of magnet coils. A compact coil structure was devised which enables electrons of up to 2.5 Mev in energy to be focused without undue rise in conductor temperature, thus preserving the feature of high precision in the measurement of relative electron momenta. For point sources the instrument is designed to achieve resolutions of 0.01%, 0.1%, and 1.0% in momentum, at transmission values of 0.08%, 0.38%, and 1.2% respectively. The use of a curved exit slit enhances the luminosity of the instrument by permitting the use of long sources.The narrowest experimental line width attained has been 0.014% in momentum at half the maximum intensity, at a transmission of 0.06% and using a source 0.1 mm in width.